In their everyday medical practice, doctors frequently encounter patients seeking advice on improving their reproductive capabilities. Surprisingly, there is currently no comprehensive set of evidence-based clinical guidelines addressing this issue. However, in early 2017, the American Society for Reproductive Medicine and the Society for Reproductive Endocrinology and Infertility published their research findings on enhancing pregnancy rates for couples or individuals without proven infertility causes.
Fertility and Age
Fertility, defined as the ability to conceive, remains relatively stable from one menstrual cycle to another in some individuals. However, in the general population, it tends to be highest during the initial months of regular sexual activity without contraceptive use or sperm entry into the female genital tract, gradually declining over time. Approximately 80% of couples achieve pregnancy within the first six months of trying to conceive. The highest monthly fertility rates occur during the first three month. There is a notable decline in fertility in women reaching 40 which is almost half as compared to those in their twenties.
While fertility decreases with age in both men and women, the impact of aging is more pronounced in females. In women, the likelihood of pregnancy significantly diminishes after the age of 35. Conversely, although men’s sperm parameters deteriorate after age 35, their fertility remains relatively stable until around age 50.
Infertility is diagnosed in couples of reproductive age who are unable to conceive after a year of regular sexual activity without contraception. However, for individuals aged 35 and older, especially women, seeking evaluation and treatment after six months of unsuccessful attempts is advisable due to the age-related decline in fertility.
Frequency of Sexual Activity
Over the past decade, several studies have accumulated data on the optimal frequency of sexual intercourse. While abstaining from sexual activity for more than five days can negatively impact sperm count, intervals of up to two days are associated with normal sperm density. The misconception that frequent ejaculation reduces sperm quality has been debunked. In fact, a study in 2015 analyzing around 10,000 semen samples found that daily ejaculation did not significantly affect sperm concentration or mobility.
Nonetheless, prolonged sexual abstinence exceeding ten days can deteriorate sperm parameters. It’s essential to note that although sperm analysis provides valuable quantitative data, it cannot definitively determine sperm fertility.
While daily sexual intercourse might not substantially improve successful fertilization, adhering to a strict schedule or timing sexual activity based on ovulation predictions can induce significant stress. This stress can negatively affect sexual desire and frequency. Therefore, couples are encouraged to engage in sexual activity every 1-2 days as this frequency maximizes reproductive capacity and minimizes performance stress.
The “Fertility Window” or “Fertile Window” refers to a period of six days, including the five days leading up to and the day of ovulation. Theoretically, this window represents the peak viability for both oocytes and sperm. Clinically, the maximum fertility interval can be determined by analyzing the menstrual cycle duration, ovulation test results, and cervical mucus characteristics.
Studies have shown that the highest fertility probability occurs when sexual intercourse takes place two days before ovulation. The chances of conception gradually decrease on the projected day of ovulation. For women with generally regular menstrual cycles, the likelihood of conceiving through a single sexual encounter increases during an extended timeframe. Clinical pregnancy probability increases from 3.2% on the 8th day of the cycle to 9.4% on the 12th day but drops to less than 2% on the 21st day. The probability of fertilization also rises with increasing sexual activity during the fertility window. Since predicting the exact day of ovulation can be challenging, couples with regular menstrual cycles are encouraged to engage in frequent sexual activity shortly after menstruation until ovulation to maximize their chances of conception.
The peak of the fertile period can vary among women with regular menstrual cycles. Approximately half of these women can accurately predict ovulation based on cycle monitoring, cervical mucus changes, libido, pain, and mood. While the ability to predict ovulation might not improve conception rates, timing sexual intercourse remains crucial. Several methods can help predict ovulation.
- Body Changes: Observing changes in body temperature and vaginal discharge can indicate fertility. Cervical mucus analysis is a straightforward and effective way to determine ovulation. The highest probability of conception occurs when cervical mucus is delicate and transparent, though its presence is not mandatory for pregnancy. Cervical mucus volume increases in the days leading up to ovulation due to rising estrogen levels and peaks 2-3 days after ovulation.
- Ovulation Kits: Ovulation tests, measuring luteinizing hormone (LH) levels in urine, are widely used to predict the period of maximum fertility. However, it’s important to note that ovulation can occur within the next two days after the LH surge, leading to approximately 7% false-positive results. While monitoring urinary LH levels can be beneficial for couples with infrequent sexual activity, cervical mucus changes can predict fertile days with equal or greater accuracy.
- Menstrual Cycle Tracking: Using a calendar or smartphone app to monitor the menstrual cycle can pinpoint fertile days.
- Ovulation Calendars: Simple online tools can calculate and predict ovulation dates based on cycle length. Ovulation Calculator on this web site uses the results from multiple studies and precisely calculates the chances of ovulation on each day of the cycle. It gives you range of days in which you are most likely to ovulate. The chances of ovulation are high in the middle of this range and low near start and end days of this range.
Sexual Behavior of the Couple
Many women believe that remaining in a supine position after intercourse aids sperm transport and prevents sperm from exiting the vagina. However, this notion lacks scientific support. Sperm can reach the fallopian tubes within 15 minutes of cervical entry and continue their journey to the abdominal cavity.
Evidence linking female orgasm to fertility is inconclusive. While orgasm might contribute to sperm transport, there is no established correlation between orgasm and pregnancy. Similarly, there is no definitive evidence connecting sexual behavior characteristics of couples to fertility outcomes.
Regarding lubricants, some can impact sperm motility in vitro. Water-based and oil-based lubricants can have varying effects. Mineral oil, canola oil, and lubricants based on hydroxyethyl cellulose are generally safe options for couples trying to conceive.
Diet and Lifestyle
Both underweight and overweight women may experience reduced fertility. Limited data exist on the correlation between body weight and fertility in ovulating women. Elevated mercury levels in the blood, often due to seafood consumption containing heavy metals, have been associated with infertility. Women planning pregnancy are advised to take folic acid supplements (at least 400 micrograms daily) to reduce the risk of neural tube defects.
Smoking has a detrimental effect on fertility. A meta-analysis involving 10,928 women who smoked and 19,128 non-smokers revealed a significantly higher frequency of infertility among smokers . Smoking has also been linked to earlier onset of menopause in female smokers, indicating accelerated ovarian follicle depletion. While smokers may experience reduced sperm count, motility, and morphology, the impact on sperm nutrition is not definitively proven.
The effect of alcohol on female fertility remains inconclusive. Some studies suggest a negative impact, while others are inconclusive with moderate alcohol consumption. A Swedish study involving 7,393 women found an increased risk of infertility among those consuming two portions of alcoholic beverages daily. During pregnancy, alcohol should be entirely avoided due to its known adverse effects on fetal development, and no “safe” level of consumption is defined. Alcohol use does not significantly affect sperm parameters in men.
High caffeine intake (>500 mg, equivalent to over 5 cups of coffee per day) has been linked to reduced fertility. However, moderate caffeine consumption (1-2 cups of coffee daily) before or during pregnancy does not appear to significantly impact fertility or pregnancy outcomes. Caffeine intake has no effect on sperm parameters in men.
Environmental toxins are recognized as potential contributors to reduced fertility. Exposure to toxins and solvents, such as those used in dry-cleaning and printing, may decrease female fertility. Men in contact with heavy metals are at a higher risk of abnormal sperm parameters. Pesticides can also negatively affect the reproductive health of agricultural workers. Avoiding or minimizing exposure to lead and industrial microwave ovens is advisable.
- The fertile window covers a six-day period ending on the day of ovulation, and its timing correlates with cervical mucus characteristics.
Frequent sexual intercourse (every 1-2 days) during the fertile window is associated with the highest pregnancy rates, although less frequent sexual activity (2-3 times a week) still offers good chances.
- Sexual positions and lying down after intercourse do not significantly affect fertility.
- Methods for detecting and predicting ovulation are useful for couples with infrequent intercourse.
- Moderate alcohol consumption (1-2 servings per day) and caffeine intake may have adverse effects on fertility.
- The time required for conception increases with age, and consultation with a reproductive specialist is recommended for women over 35 after six months of unsuccessful attempts to conceive.
- For individuals with regular menstrual cycles, engaging in sexual activity every 1-2 days from the start of the fertile window maximizes the chances of fertilization.
- Couples trying to conceive should avoid smoking, excessive alcohol consumption (>2 servings per day), and most vaginal lubricants.
- Exposure to environmental toxins and solvents, heavy metals, and pesticides can potentially reduce fertility, and precautions should be taken to minimize such exposures.