7 Factors That Affect Fertility

One out of every eight couples have trouble getting pregnant or staying pregnant.

Medically reviewed in August 2020

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Infertility, or the inability to conceive, can be extremely emotional—whether you’ve been trying for just months or for many years. Every couple has a unique set of circumstances and thus, fertility success is dependent upon many factors.

According to the Centers for Disease Control and Prevention (CDC), one in every eight couples have trouble getting pregnant or staying pregnant. Some causes of infertility are controllable and avoidable, while others aren’t.

If you’re trying to become pregnant, or even looking ahead to the future, there’s more to it than age (women over 35 have an increased risk of infertility). We spoke with OBGYN Peter Nassar, MD, of Saint Agnes Medical Center in Fresno, California to learn how he prepares his patients for conception, and some of the factors that can affect a couple’s fertility. Here’s what he had to say.

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Ovulation and other factors

First things first: It may seem like some women can get pregnant at the drop of hat—and while that’s wonderful, it takes a while for many others. And if you think about it, it makes sense—our bodies are amazing, but everything has to be timed just right for success.

“To get pregnant, you need an egg, a functional ovary, a good, healthy sperm count, a meeting place for the sperm and egg, and you need to have sex during ovulation so all of this can happen,” says Nassar. In a nutshell, this means the sperm has to travel through the uterus of the woman and join with her egg that’s traveling down one of her fallopian tubes from the ovary to the uterus. And it’s only during ovulation—usually sometime between days 10 and 14 of a woman’s menstrual cycle—that women release a mature egg.

All of that to say, there are a lot of components to conception and you shouldn’t get discouraged if they don’t align right away. The process of trying to conceive can be very exciting for you and your partner. But if things aren’t going as planned, there may be some other factors at play.

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Unhealthy sperm or low sperm count

When it comes to fertility, it's not just the woman's organs that have to work properly-a man's sperm obviously plays a large role, too. Although most infertility research is centered around a woman's reproductive health, findings from a 2017 analysis may encourage a closer look at male fertility. 

The study, conducted by the Hebrew University-Hadassah Braun School of Public Health and Community Medicine in Jerusalem, analyzed 185 sperm count studies from countries around the world and found that sperm counts have dropped almost 60 percent over the last 40 years in North America, Europe, Australia and New Zealand. Researchers admit they're not confident about why these numbers are declining, but there are some theories-and Nassar agrees. 

Anything that damages the sperm may cause fertility issues. Varicoceles-that is, enlargements of the veins within the scrotum (the bag of skin that holds the testicles)-can reduce sperm count and damage the quality of the sperm, says Nassar. Most varicoceles don't require treatment, but if they're causing pain or a fertility specialist determines they're interfering with your ability to conceive, your partner may need surgery. 

Increased temperature to the testicles is another cause of low sperm count. "We discourage men from using saunas or hot tubs, and we always say to wear loose underwear rather than tight. Tighter underwear can increase the heat down there," Nassar says. He recommends that truck drivers in particular should beware of sitting on warm cloth seats for long periods of time, since that can increase the temperature of the testicles and decrease sperm count. And, leaving laptops propped on the lap for long periods of time can also increase temperature. 

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Sexually transmitted infections (STIs)

STIs can affect both a woman and a man’s fertility.

For a man, STIs like chlamydia affect their sperm. “STIs can affect the ejaculatory ducts that the sperm pass through. They can cause scarring of the ducts, and that can cause damaged sperm and decreased count,” says Nassar.

For a woman, STIs like chlamydia and gonorrhea can cause pelvic inflammatory disease (PID), an infection of a woman’s reproductive organs. PID is an infection of the upper genital tract that can permanently damage the fallopian tubes and uterus, among other issues.

It’s important to stay up-to-date with your screenings and practice safe sex. The CDC does not recommend screenings for the general population. However, the CDC does suggest all sexually active women ages 25 and younger, and any older women who are at an increased risk, get the screening for chlamydia and gonorrhea every year. Annual screenings for chlamydia and gonorrhea should also be done annually for men who have sex with men or any man who is exposed to or has had previous exposure to the infections.

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Drug and substance abuse

When it comes to drug and tobacco use and infertility, existing evidence is sparse, but Nassar says recreational substances can impact fertility.

“Marijuana, tobacco and illicit drugs can actually decrease a man’s sperm count, prevent the sperm from being able to move and can cause an increase in defective sperm,” says Nassar. But available research does not yet prove a direct link between smoking and a decrease in male fertility.

One large meta-analysis of nearly 11,000 smoking women and 19,000 nonsmoking women showed that there was a substantial increase in infertility issues in smokers when compared to nonsmokers. And if you’re wondering about alcohol, the American Society for Reproductive Medicine states that higher levels of alcohol consumption—that is, more than one to two drinks per day—should be avoided when attempting pregnancy.

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Weight issues

More American women are obese before pregnancy than ever before. In fact, fewer than half of women are at a healthy weight before conceiving. And while it’s possible to get pregnant if both partners are overweight or obese, you might have a better chance if you’re both at healthy weights.

“In general, obesity by itself can decrease the quality of a man’s sperm. On top of that, fat tissue in men and women secretes estrogen, and if estrogen levels increase in a man, it can lead to a decrease in sex drive, irregular testosterone levels and erectile dysfunction, which all affect fertility,” says Nassar.

And obesity on the woman’s side plays a part, too. Nassar explains that fat tissue also makes estrogen, which can affect your hormone cycle. “These hormonal changes make your body think that you don’t need to produce estrogen from your ovaries, which can halt ovulation.”

If you tend to yo-yo diet, weight fluctuations can shock your body into thinking you’re under stress, says Nassar. “When your body thinks it’s under stress, you may stop ovulating.” Being underweight can shock your body, too, so maintaining a healthy weight is ideal.

Nassar says to remember that everyone has their own threshold. “Some patients who are normally 120 pounds get to 127 pounds and they stop ovulating. But I’ve had other patients who are 270 pounds who ovulate every month and get pregnant, no problem.” In general, maintaining a healthy weight can lower your overall health risks. Try adopting a well-balanced diet, getting good quality sleep and getting regular exercise.

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Stress is a Catch 22—if you’re having problems with infertility, you’re understandably going to be stressed. But stress of any kind—even if it’s low level—might play a role in fertility. If you’ve been trying, it’s likely you’ve heard “Just relax! or “Try not to think about it and it will happen.” While those are kind words of encouragement, the fact of the matter is, it’s going to be on your mind.

While there isn’t any proof that stress can cause infertility, stress may impact your cycle. “If you have major stressors in your life, it can affect your hormone balance and throw off your ovulation, making it harder to produce or release eggs,” says Nassar. So, whether your stress is related to infertility, work, caregiving or a combination of all, you may want to practice stress relief exercises if you’re trying to get pregnant. Here are some ideas:

  • Write out both your negative and positive thoughts in a daily journal.
  • Try meditation—spend 5 minutes in the morning in a quiet place listening to your breath.
  • Exercise, but remember that extreme exercise could impact ovulation. Listen to your body and if you push it too hard, back off for a bit.
  • Take some time for yourself—a quiet morning sipping coffee or a relaxing bath before bed can help you relax.
  • Take the pressure off by setting aside time to do fun things and enjoying each other—yes you’ll have sex, but make it fun!
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Hormonal issues and health conditions

There are a variety of women’s health conditions that cause fertility problems. These conditions can prevent fertilization, implantation or a successful pregnancy:

  • Endometriosis
  • Pelvic inflammatory disease
  • Polycystic ovarian syndrome
  • Uterine scarring from a dilation and curettage (D&C) surgery after miscarriage
  • Diabetes
  • Thyroid disorders
  • Uterine fibroids

It’s important to talk with your doctor before you try to conceive if you have one of these conditions. You’ll want to be sure you have symptoms under control before you start trying.

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3 More ways to increase fertility

Every couple is different, so you have to be mindful that what may be affecting your fertility may not play a part in a friend or family member’s ability to get pregnant. The same holds true for things you can do to increase your chances. Still, there are a few things Nassar recommends trying:

  1. Take note of your cycle and your symptoms
    Before you try to conceive, it’s best to start tracking your menstrual cycle, taking note of symptoms like blood flow and cramps, so you can share them with your OBGYN, says Nassar.
  2. Have sex during ovulation
    Since you have to have sex at the right time (when you’re ovulating), you’ll need to know when you’re ovulating. You may be able to increase your chances of fertility when it comes to timing by: 
    • Investing in surge kits that can predict your day of ovulation
    • Testing your basal body temperature; temperature usually increases during ovulation
    • Observing your vaginal discharge—it usually looks like egg whites and is thin and stretchy in consistency during ovulation
  3. See your doctor
    Most OBGYNs suggest that if you’ve been trying for a year and haven’t become pregnant, consult with your OBGYN or a fertility specialist. Women over 35 may want to see their doctor after 6 months of trying. Your healthcare provider can help determine what may be going on and treat any conditions or issues to help increase your chances of getting pregnant. “I have a lot of patients who wait for years because they didn’t know their doctor could help them make one little hormonal change that would help them ovulate, or that their sperm count was low, and that we look into things like that,” Nassar says. “You don’t have to go through it alone. Talk to your OBGYN so they can help you come up with a plan.

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