- Generally, most experts define infertility as not being able to get pregnant after at least one year of trying.
- Women who are able to get pregnant but then have repeat miscarriages are said to be infertile.
- Men are said to be infertile when their semen analysis returns readings below the WHO minimum for sperm count, motility (progressive movement), morphology (shapes) and various other key parameters.
- A woman must release an egg from one of her ovaries (ovulation).
- The egg must go through a fallopian tube toward the uterus (womb).
- A man’s sperm must join with (to fertilise) the egg along the way.
- The fertilized egg must attach to the inside of the uterus (implantation).
Infertility can result from a multitude of problems, which can interfere with any of these steps.
Everybody is different. Some couples fall pregnant quickly, while for others it may take some time. As a general rule, if you and your partner have been unsuccessful in trying to conceive for around twelve months then you may want to consult a fertility specialist. This applies to couples that have unprotected intercourse approximately three times a week and are both under 35. For couples over 35, it’s recommended to seek advice after six months of trying to conceive. This is because fertility significantly declines from the mid-thirties onwards and the sooner professional help is sought, the better the chance of identifying and resolving any problems. Other circumstances where it is important for women to seek advice from a fertility specialist are if you suffer from health conditions such as Pelvic Inflammatory Disease (PID), Endometriosis, Fibroids, Polycystic Ovarian Syndrome (PCOS), or diabetes. Anyone with a history of thyroid problems, irregular menstruation, or cancer, is also encouraged to talk to a specialist. Ideally you don’t want to leave it too long and should consult someone after six months of trying to fall pregnant. Men with erectile dysfunction should seek advice from a doctor. It’s also a good idea to have a fertility specialist analyse a semen sample to identify any possible abnormalities. In many circumstances, these problems can be addressed and fertility enhanced. In all cases, a fertility specialist will be able to give you a full health assessment. A specialist may carry out tests to determine if there are underlying medical conditions inhibiting conception. Often couples will conceive quickly once the condition is treated.
If you have actively been trying to fall pregnant for a year and been unsuccessful, a physician will typically diagnose infertility. The definition given for actively trying to conceive is having unprotected sex at least once every two to three days. A physician will offer consultation and make treatment recommendations to women younger than 35 after a year of failed conception. In some cases, women with known medical conditions or who are over the age of 35, fertility specialists will provide treatment and consultation after only six months of actively trying to conceive Fertility physicians will seek a full medical history and may perform certain tests to determine reproductive status. This may include specialised blood tests, sperm analysis, ultrasounds, and full physical examinations. This consultation will help to assess the probable cause of infertility. In many cases, certain lifestyle changes can be made to significantly enhance conception chances.
The principal cause of infertility for women is problems with ovulation. However, there has been a lot of research into different treatments. Scientists have developed medications such as Clomiphene and Menogan/Repronex that can treat approximately 70% of ovulation problems. There are many causes for ovulation failure. Some of the more common underlying triggers include scarred ovaries, hormone imbalances, follicle problems, and premature menopause. Another common cause of female infertility is Endometriosis. This gynecological condition affects over 1.5 million women in the United Kindom, costing the NHS on average £8 billion annually according to Helen North, Chief Executive of Endometriosis UKhttps://endometriosis-uk.org/news/press-release-its-ok-talk-period-endometriosis-uk%E2%80%99s-awareness-week-campaign-%E2%80%93-3rd-9th-march#.U-YOZvmSzWR.. Studies suggest that almost 10% of women that report fertility issues have endometriosis”Bulletti, C. et. al. (2010) Endometriosis and infertility. Journal of Assisted Reproduction and Gentics, Volume 27, Issue 8, (pp. 441-447).”. Furthermore, it’s estimated that up to 40% of these women are considered infertile as a result of this condition. Women affected by endometriosis have a lower probability of conceiving during ovulation than women without the condition. In some cases, infertility in women can arise due to abnormality in the uterus, including problems with cervical mucus. Lifestyle choices can also hinder fertility, such as alcohol and drug use, plus insufficient nutrition.
Male infertility is as equally common as female infertility. A reproductive specialist can assess sperm count, morphology, and motility to help to determine if these important parameters are within the healthy range. This is a straightforward laboratory analysis of a fresh semen sample. There are a range of treatment options available to men that have abnormalities with any of these assessments. In some situations the health of the sperm is normal, although there are problems with the ejaculatory duct. Blockages can prevent the sperm from ejaculating, leading to infertility. Another common cause of male infertility is a condition called varicocele. This is similar to a varicose vein, yet located in the scrotum. When a varicocele is present, scrotum temperature is elevated. When sperm gets too hot it suffers damage that can lower fertility and make conception difficult. There are a variety of treatments that can help fertility. Some common options are artificial inseminations, different fertility drugs, and intracytoplasmic sperm injections (ICSIs). However, simple lifestyle changes such as eating a balanced, healthy diet, staying fit, and avoiding stress, can also improve sperm health and fertility in many instances.
Fertility experts advise couples to have sex at least three times a week to increase the chance of conception. Actively trying to conceive rather than trying to identify when you are most fertile is a more reliable approach. This is the most successful way to fall pregnant naturally. Although, it can be helpful to know when you are at peak fertility so that you can increase sexual activity during this period. If you are able to determine when you are ovulating then it’s easy to know when you are most fertile. This requires being familiar with your menstrual cycle. If your period is regular then it is a simple calculation to find out when you are ovulating. In most instances this is about two weeks before your period is due. Even if your menstruation cycle is irregular, it’s still possible to chart when you are most likely to be ovulating. This can be done by recording your basal body temperature (BBT). Your BBT is your temperature when you wake up first thing in the morning, or after a minimum of three hours of uninterrupted sleep. This temperature needs to be recorded using a special basal thermometer and should be done before you get out of bed. When you’re ovulating your BBT will be slightly elevated compared with other readings. You can also purchase specialised ovulation predictor kits. These help to pick up changes in hormone concentrations in your urine before you are due to ovulate. They are very accurate, although it can become expensive if you have to purchase new kits monthly. Paying closer attention to cervical mucus can also be a way to monitor ovulation times”Flynn, A. and Lynch, S. (1976) Cervical mucus and identification of the fertile phase of the menstrual cycle. BJOG: An International Journal of Obstetrics & Gynaecology, Volume 83, Issue … Continue reading. When this mucus becomes clear and increases in volume, the body is entering into a fertile window. This will last for a few days. Once ovulation has occurred, cervical mucus will become dry, or cloudy and streaky. Often fertility specialists will recommend having unprotected intercourse every day or every second day beginning five days prior to ovulation. It’s advised to continue this pattern during ovulation. This will increase the chance of falling pregnant.
In the UK approximately one in seven couples has problems conceiving. This equates to around 3.5 million people. Generally, 84% of couples are able to conceive naturally within a year if they are actively trying to conceive. Statistics show that for every 100 couples trying to fall pregnant naturally
- 84 will conceive within 1 year
- 92 will conceive within 2 years
- 93 will conceive within 3 years
Those couples that have been trying to fall pregnant for over three years without success, the chances of conception within the next 12 months are 25% or less. For couples unable to conceive naturally IVF treatment may be an option. Success with IVF depends on a wide range of factors including age and the cause of fertility. Statistics released by the UK Human Fertilisation & Embryology Authority show that in 2011, just over 25% of IVF treatments using a woman’s own fresh eggs lead to a successful pregnancyhttps://www.hfea.gov.uk/. Approximately 2% of babies born in the UK are a result of IVF treatment. However, IVF isn’t recommended for women older than 42. This is because the chances of successfully conceiving are believed to be too low.
A normal sperm count is a minimum of 20 million per millilitre of ejaculate. For most men the average count is 60 million/ml. For some men, sperm count can be over 200 million/ml. A sperm count of zero is indicative of a blockage somewhere in the male reproductive system. However, it’s important to recognise that it isn’t just the volume of sperm that’s important for fertility. Good motility is also essential. Sperm need to be able to pass through the fallopian tubes in order to fertilise the egg. A minimum of 50% of sperm with healthy motility is needed to make fertility easier. Also, sperm needs to have healthy morphology. The chances of conception may be increased with treatments for low sperm count. Hormone medications may restore normal sperm count in cases where a hormonal balance is identified. These medications can boost sperm production and assist with motility. If there’s a blockage within the reproductive system, surgery may be required. This is especially the case if there is zero sperm count. Often once the corrective surgery has been completed, conception is much easier. There are also many other factors that can affect sperm health. Stress, illness, poor diet, excessive drug and alcohol use, and insufficient exercise; these can all influence the amount of sperm available and its quality. It’s important to keep in mind that it takes three months for sperm to fully mature. If there are negative influences during this time, sperm health can be adversely affected.
Poor diet can seriously affect sperm mobility. Deficiencies in certain amino acids, vitamins and minerals can reduce sperm health and slow vigour”Wong, W. et.al. (2000). Male factor subfertility: possible cause and the impact of nutritional factors. Fertility and Sterility, Volume 73, Issue 3, (pp. 435-442).”. Fertility specialists will always encourage both men and women to maintain a healthy, balanced diet while trying to conceive. There are also certain medications that can cause sperm irregularity and impaired motility. In particular, steroids and hormone medications can be harmful to motility”Nudell, D. et. al. (2002) Common medications and drugs: how they affect male fertility. Urologic Clinics of North America, Volume 29, Issue 4, (pp. 965-973).”. Other lifestyle choices such as alcohol consumption and use of marijuana and tobacco may decrease sperm motility. It is still possible to conceive, even with a low percentage of motile sperm. However, it can take a lot longer to fall pregnant. The good news is that there are a range of treatments available that can assist to increase the quality, quantity, and the motility of sperm.
Many researchers believe that conception chances can be enhanced by the female orgasm. Uterine contractions assist with propelling the sperm forward into the cervix. Also, if a woman has an organism during sex, it’s more likely that she is feeling relaxed and stress-free. This is important for conception as stress can impede fertility. For men, if the sex is particularly satisfying, research show that the volume of ejaculate can be up to 50% more due to elevated stimulation. Taking the time to improve sex for both partners can help to enhance fertility and improve the chances of conception.
Also known as IVF, in-vitro fertilisation is the process of using a male’s sperm to fertilise a woman’s egg outside of the body. This has sometimes been referred to as having a “test tube baby”. Once the egg is fertilised, it is then transferred into the woman’s uterus. The age and health of the woman will determine how many embryos are transferred into the uterus. Also, the country where the woman lives is a consideration. Some countries restrict the number of healthy embryos that can be transferred. The chance of successful implantation is high with the increasing number of embryos transferred. In some instances, several embryos may be transferred, yet only one or none will successfully implant. In other cases, many or all of the transferred embryos are successfully transferred. This leads to multiple births. This is a major consideration for many couples. There is a potential risk to the health of both the mother and unborn babies in the case of multiple foetuses. Most fertility specialists in the UK will only transfer 2 or 3 of the healthiest embryos in an IVF treatment.
You may be considered suitable for IVF treatment if you and your partner have been trying actively to conceive for more than 12 months and other forms of reproductive avenues have been explored without success. There are also certain conditions that may help to determine your suitability. This may include fallopian tube dysfunctions, PCOS, PIF, endometriosis, uterine issues, cervical mucus problems, failed IUI, and unexplained infertility.
For women with regular periods, determining when ovulation takes place can be easy. Usually ovulation occurs around 14 days before the start of menstruation. This calculation is based on a 28 day cycle. However, not all women have this cycle regularity. It’s recommended to follow your cycle carefully for a few months to determine length and month to month variations. There are plenty of different ovulation calculators. These can be helpful to women wanting to determine their most fertile times during each cycle. They can assist women with regular and irregular cycles. In addition to keeping track of dates, being familiar with your body can also help. Many women experience tell-tale signs that they are ovulating. A slight twinge or cramp in the abdomen can be an indication that menstruation will soon start. However, not all women will get these signs that her body is starting to release an egg. Another way to keep track of ovulation is by tracking Basal Body Temperature (BBT). Charting BBT daily will give an accurate account of your hormone levels and when ovulation is about to occur. Some women can also determine when they are ovulating by monitoring changes in cervical mucus throughout their cycle. As the egg gets ready to be released, cervical mucus changes in concentration and consistency.
It’s important to be familiar with the biphasic temperature curve if you are monitoring you Basal Body Temperature (BBT). During the middle of your cycle the biphasic temperature curve is present. It usually has two phases. The first phase is the follicular phase and this starts just before ovulation when temperature is lower. The corpus lateum phase is the second stage that occurs after ovulation. During this second phase there is an average increase of temperature of 0.02 degrees. Although this may not seem like a significant increase, with a speciality thermometer it’s possible to identify this rise in temperature that signals the start of ovulation. As the window is small, knowing precisely when you are about to ovulate can assist in determining the optimal time for sex.
In some cases, ovarian cysts can contribute to lower fertility. Depending on the location and type of cyst, they may cause difficulty with conception or even infertility. There are many different types of cysts. Endometriosis can cause endometrioma cysts that cause fertility problems, as well as Polycystic Ovarian Syndrome (PCOS) cysts. These are the two main cyst-causing fertility problems. There are also other forms of ovarian cysts which aren’t as problematic. These may include cyst adenomas, dermoid cysts and functional cysts. The most common are functional cysts. They tend to be classified as either corpus luteum cysts or follicular cysts. These develop during menstruation cycles and don’t lead to infertility. They are actually strong signs that that the reproductive system is actually healthy and working correctly. Nether cyst adenomas or dermoid cysts negatively affect fertility. Cyst adenomas do require treatment however. If these types of cysts get too big they can cause infertility problems.
Some women with PCOS are still able to get pregnant without the assistance of IVF or reproductive technologies. However, if you do suffer from PCOS, conception can be difficult due to the absence of menstrual cycles or significant irregularities. Despite this, many women are able to naturally conceive by meticulously keeping a fertility chart and making positive lifestyle changes. This many include changing diets to include foods that promote healthy menstrual cycles, having regular sexual intercourse frequently, and not stressing about conception. There are many cases of women accidently falling pregnant despite having PCOS.
Pelvic Inflammatory Disease (PID) is an infection that affects the reproductive system. With every PID episode, fertility decreases”Westrom, L. et.al. (1992). Pelvic inflammatory disease and fertility: A cohort study of 1,844 women with laparoscopically verified disease and 657 control women with normal laparoscopic … Continue reading. Thus, it’s very important to frequently monitor for STIs, and other infections to reduce the risk and duration of PID. The faster a PID is identified, the quicker it can be treated and the lower the risk of infertility. If you have experienced PID, scar tissue may have formed within your fallopian tubes. In serious cases this may stop sperm from accessing the egg or cause the embryo to become blocked. If sperm is able to fertilize the egg but unable to move to the uterus, there is a high chance of having an ectopic pregnancy. This pregnancy will need to be terminated through surgery or taking certain medications. It is still possible to conceive and have a healthy pregnancy and baby despite having had PID. Nevertheless, this isn’t without risk. It can still be difficult to conceive naturally. IVF or ICIS may be necessary.
Couples trying to have a baby can be devastated by miscarriages. The emotional and physical distress can be overwhelming and many couples are left trying to figure out what went wrong. The reality is that there are no definite causes for most miscarriages. Research shows that one quarter of pregnancies end in a miscarriage. It’s very important for couples to understand that miscarriages can just happen; even if you did everything you could do during the pregnancy to support a healthy foetus. However, some factors can contribute miscarriage, such as hormonal problems, anatomical abnormalities, genetics, infections, immunological issues, and the use of alcohol and other drugs during pregnancy. It’s always a good idea to discuss when it’s the best time to try and conceive again with your obstetrician or gynaecologist after having a miscarriage. Most fertility specialists will encourage couples to wait until after the woman’s next period before trying to conceive again. In some cases, it may be advised to wait even longer before trying again. This will depend on individual circumstances and reproductive health. If the cause of miscarriage is known, then it may be possible to treat the problem so that it doesn’t happen again. In some instances, it may not be safe to conceive again without treatment or medical assistance and supervision.
Basal Body Temperature (BBT) charting is a method woman can use to work out when they are ovulating. Charting your BBT throughout the month allows you to identify minor changes in body temperature that reflect hormonal changes. Before ovulation, oestrogen levels are higher. However, during and after ovulation, progesterone levels increase. Generally, BBT is lower prior to ovulation and it will increase slightly as progesterone concentrations increase. This rise in BBT can be used to determine the best times to try and conceive. It’s always a good idea to chart your BBT for a few months. This will allow you to obtain a more accurate calculation. After a few months, you should be able to identify you normal BBT prior to ovulation, plus during and after ovulation.
Pre-conception care is the process of seeking medical advice and care prior to trying to conceive. This can help both partners to determine if there are any health issues that may make conception difficult or prevent a healthy pregnancy. During these consultations, a fertility specialist will carry out a thorough medical exam and document personal and family medical history. By evaluating history, laboratory analysis, and physical examinations, any potential risks or complications can be identified. If there are potential problems identified with either partner, the doctor can then make recommendations for suitable treatments. This may involve simple adjustments to lifestyle such as improving diet and exercising more regularly. Essentially, pre-conception care helps to ensure that both partners are in good reproductive condition to improve the chances of conception. If there are problems identified, pre-conception care provides an opportunity to have complications addressed before trying to fall pregnant.
If you or your partner smokes, it will affect fertility. Compared with women that don’t smoke, studies show that women who smoke around 10 cigarettes a day are less fertile. Not only does it take longer to conceive, the risks of miscarriage are also higher. Smoking can also reduce sperm count and quality, lowering male fertility”Levin, R. et.al. (1982). Effects of psychotropic drugs on human sperm motility. Obstetrical & Gynecological Survey, Volume 37, Issue 7 (pp. 484-486).”. Second hand smoke is almost as damaging as personally smoking. It’s highly advised that neither partner smokes when trying to conceive. Not only is smoking damaging to your health and fertility, it can also be very dangerous for your baby during and after pregnancy. Smoking during pregnancy is known to contribute to infant morbidity and mortality. A new study has found that foetal exposure to tobacco smoke may influence the development of certain diseases later in life by modifying certain genes“Markunas, C. et. al. (2014). Identification of DNA Methylation Changes in Newborns Related to Maternal Smoking during Pregnancy, Environmental Health Perspectives, DOI:10.1289/ehp.1307892.”. Sudden Infant Death Syndrome (SIDS) is often associated with parents that smoke. A recent meta-data analysis evaluating 35-case controlled studies confirms that there is a link between maternal smoking and a high risk of SIDS“Zhang, K. And Wang, X. (2013). Maternal smoking and increased risk of sudden infant death syndrome: A meta-analysis. Legal Medicine, Volume 15, Issue 3, (pp. 115-21)”.. This elevated risk is also identified with infants that co-sleep with postnatal smoking parents.
Studies have shown that women who smoke marijuana have fertility problems. Research indicates link between marijuana usage and irregular periods, poor libido, hormonal fluctuations, and miscarriage“Mueller, B. et.al. (1990). Recreational drug use and the risk of primary infertility. Epidemiology, Volume 1, Issue 3, (pp. 195-200).”. Other studies have shown that men who smoke marijuana have a reduced sperm count, poor sperm motility, and ejaculation problems“Barazani, Y. et. al. (2014). Lifestyle, Environment, and Male Reproductive Health. Urologic Clinics of North America, Volume 41, Issue 1, (pp. 55-66).”. Smoking marijuana can negatively affect fertility and reduce conception chances. This also applies to people that are trying to conceive using IVF treatments“Klonoff-Cohen, H. et.al. (2006). Aprospective study of the effects of female and male marijuana use on in vitro fertilization (IVF) and gamete intrafallopian transfer (GIFT) outcomes. American … Continue reading.
There are a wide range of medications that can negatively impact fertility. Women trying to increase muscle mass by using anabolic steroids will have difficulties conceiving“Maravelias, A. et.al. (2005). Adverse effects of anabolic steroids in athletes: A constant threat. Toxicology Letters, Volume 158, Issue 3, (pp.167-75).”. Anabolic steroids elevate testosterone levels. This can significantly lower fertility and negatively affect a woman’s chance of falling pregnant. There are various anti-anxiety and anti-depressant medications that can inhibit ovulation. Anti-histamine medications should be avoided while trying to conceive. Also, decongestant medications can negatively affect fertility as they alter the cervical mucus. Decongestants can reduce the concentration of the mucus, making it difficult for the sperm to penetrate the cervix. Male fertility is also negatively impacted with anabolic steroid use. It can lead to becoming completely sterile“Leme de Souza, G. and Hallak, J. (2011). Anabolic steroids and male infertility: a comprehensive review BJU International, Volume 108, Issue 11, (pp.1060-5).”. Men also risk fertility problems by taking herbal testosterone enhancers. Even if you cease taking these supplements, it can take up to six months before viable sperm can be produced again. Research has suggested that 40% of men that use Tagamet ulcer medication become impotent. Studies show that this medication and other similar medications can significantly damage sperm health”Koukkou, E. et.al. (2005). Environmental and drug induced erectile dysfunction. ANIR -ANHP, Volume 7, Issue 4, (pp. 171-176).” . The quality and quantity of sperm may also decrease with the use of some Irritable Bowel Syndrome (IBS) medications. There has also been suggestions that herbal remedies such as St. Johns Wort, Echinacea, and gingko biloba can reduce the ability of sperm to penetrate and fertilise the egg. It’s always a good idea that you and your partner discuss any medications or herbal supplements you are taking with a fertility specialist before trying to conceive. This can help to identify any potential fertility issues and alternative options that won’t reduce your chances of conceiving.
ICSI is short for Intracytoplasmic Sperm Injection. This method of conception is sometimes used when male fertility problems are causing difficulties conceiving. ICSI is a procedure where the male’s sperm is directly injected into the female’s egg. This procedure is often used when low sperm count or poor sperm motility is identified. ICSI may also be recommended if the male’s sperm can’t penetrate the egg and fertilize it, or there is a anatomical abnormality or blockage that stops the production of sperm in ejaculate. Couples that have previously been unsuccessful with IVF treatment may also wish to consider ICSI.
IUI is short for Intrauterine Insemination, also often referred to as artificial insemination (AI). During an IUI procedure, a long catheter is used to transfer washed sperm into the woman’s cervix. This procedure is performed at the most fertile stage of a woman’s ovulation cycle. Often an IUI treatment is one of the first procedures offered when couples are having difficulties conceiving naturally. Although it has a lower success rate compared with IVF treatment, IUI is much cheaper. For this reason, most couples are able to attempt IUI several times. Generally IUI is used in situations where the male sperm count is low or motility is poor, or for women with abnormalities in cervical mucus. This procedure may also be used when a donor sperm is needed for conception. There may be other situations that cause infertility where IUI is a suitable treatment to help couples conceive.
If your periods are irregular, you can still take measures to improve chances of natural conception. It’s a good idea to chart you Basal Body Temperature (BBT). You may need to pay closer attention to your cycles compared with women with regular periods. The easiest way to increase your conception chances is to have frequent unprotected sexual intercourse. Have sex every day or every other day to increase your chance of conceiving naturally. Making healthy lifestyle choices is also important. Maintain a healthy, balanced diet, exercise regularly, try to eliminate stress or stressful situations, don’t smoke, and reduce or stop your intake of alcohol. It’s always a good idea to discuss the impact of any medications you and/or your partner may have on conception. There are also a range of natural supplements that can help to bolster fertility.
Research has shown that between 30 and 50% of infertile women have Endometriosis“Haydon G. (1942). A study of 569 cases of endometriosis. American Journal of Obstetrics Gynecology, Volume 43, (pp. 704)”. This does not suggest that all women suffering from Endometriosis are infertile. However, many women with this condition suffer from fertility problems and are either unable to conceive or will have difficulties conceiving. There are surgical procedures and other treatments that may elevate the chance of conceiving even if you suffer from this condition. IVF or other assisted reproductive technologies may be useful. A fertility specialist will be able to assess your health and propose an appropriate course of action.
Didn’t find your answer?
|↑2||”Bulletti, C. et. al. (2010) Endometriosis and infertility. Journal of Assisted Reproduction and Gentics, Volume 27, Issue 8, (pp. 441-447).”|
|↑3||”Flynn, A. and Lynch, S. (1976) Cervical mucus and identification of the fertile phase of the menstrual cycle. BJOG: An International Journal of Obstetrics & Gynaecology, Volume 83, Issue 8, (pp. 656-659).”|
|↑5||”Wong, W. et.al. (2000). Male factor subfertility: possible cause and the impact of nutritional factors. Fertility and Sterility, Volume 73, Issue 3, (pp. 435-442).”|
|↑6||”Nudell, D. et. al. (2002) Common medications and drugs: how they affect male fertility. Urologic Clinics of North America, Volume 29, Issue 4, (pp. 965-973).”|
|↑7||”Westrom, L. et.al. (1992). Pelvic inflammatory disease and fertility: A cohort study of 1,844 women with laparoscopically verified disease and 657 control women with normal laparoscopic results. Sexually Transmitted Diseases, Volume 19, Issue 4, (pp. 185-192).”|
|↑8||”Levin, R. et.al. (1982). Effects of psychotropic drugs on human sperm motility. Obstetrical & Gynecological Survey, Volume 37, Issue 7 (pp. 484-486).”|
|↑9||“Markunas, C. et. al. (2014). Identification of DNA Methylation Changes in Newborns Related to Maternal Smoking during Pregnancy, Environmental Health Perspectives, DOI:10.1289/ehp.1307892.”|
|↑10||“Zhang, K. And Wang, X. (2013). Maternal smoking and increased risk of sudden infant death syndrome: A meta-analysis. Legal Medicine, Volume 15, Issue 3, (pp. 115-21)”.|
|↑11||“Mueller, B. et.al. (1990). Recreational drug use and the risk of primary infertility. Epidemiology, Volume 1, Issue 3, (pp. 195-200).”|
|↑12||“Barazani, Y. et. al. (2014). Lifestyle, Environment, and Male Reproductive Health. Urologic Clinics of North America, Volume 41, Issue 1, (pp. 55-66).”|
|↑13||“Klonoff-Cohen, H. et.al. (2006). Aprospective study of the effects of female and male marijuana use on in vitro fertilization (IVF) and gamete intrafallopian transfer (GIFT) outcomes. American Journal of Obstetrics & Gynecology, Volume 194, Issue 2, (pp. 369-76).”|
|↑14||“Maravelias, A. et.al. (2005). Adverse effects of anabolic steroids in athletes: A constant threat. Toxicology Letters, Volume 158, Issue 3, (pp.167-75).”|
|↑15||“Leme de Souza, G. and Hallak, J. (2011). Anabolic steroids and male infertility: a comprehensive review BJU International, Volume 108, Issue 11, (pp.1060-5).”|
|↑16||”Koukkou, E. et.al. (2005). Environmental and drug induced erectile dysfunction. ANIR -ANHP, Volume 7, Issue 4, (pp. 171-176).”|
|↑17||“Haydon G. (1942). A study of 569 cases of endometriosis. American Journal of Obstetrics Gynecology, Volume 43, (pp. 704)”|