Wellness and Healthy Living: BJC Medical Group


Published on Wednesday, December 13, 2017

Maximizing fertility

By Cory Miller, MD

So, you’re thinking about getting pregnant, but maybe you’re a little confused by the wide variety of information about how to maximize your chances. Should you stay lying down for an hour after sex? Should you have sex every day or every other day? Do you need to use ovulation predictor kits to know when the time is right? I think it’s worthwhile to give just a few basic suggestions to help you on the road to pregnancy, when you’re ready.

How old is too old?

There’s really no right answer to this, and lots of women of all ages have happy and healthy pregnancies. However, we know that pregnancy rate diminishes more sharply after around 35 years old. This is also around the stage of life where we see a sharp increase in the risk of genetic abnormalities such as Downs Syndrome. This doesn’t mean it’s unsafe or unreasonable to expect pregnancy after 35, but that a little more care and attention may be required. While we would typically give a younger couple about 12 months of trying on their own before starting to evaluate for infertility, we’ll usually shorten that length to 6 months for women over 35.

How often should we have sex?

It seems that daily or every other day is probably best. The quality of men’s semen goes down pretty badly after 5 days of abstinence. However, there doesn’t seem to be much change in quality or pregnancy rates in couples who have sex every day versus every other day, during their fertile window around ovulation.

When’s the best time in my cycle to get pregnant?

Let’s call this your fertility window, and it seems to be best around the 5-6 days before ovulation. That’s not to say you might not conceive any day of the cycle, but that the highest fertility rates happen just a couple days before ovulation. Most women have cycles around 28 days in length, measured from the first day of one menses to the first day of the next. If we mark the first day of menstrual bleeding as day 1, this means that the best time to get pregnant is going to be around days 9-17, with ovulation happening around day 14. Of course, this is variable woman to woman, and it’s not abnormal for cycle length to be anywhere between 21 and 35 days. Because of this, many women prefer to track cycles and ovulation, and there are lots of great apps for your smartphone that can help you keep track, and even alert you, to your predicted best times.

You may also find it useful to use ovulation predictor kits, available over the counter or online. They will tell you about two days before ovulation, which is a great time for fertility. A cheaper option is watching for cervical mucus changes.  There is an appreciable change in consistency of cervical mucus to a slippery, clear consistency at the time of maximum fertility, which is about 2-3 days before ovulation.

Alright, do I have to lie down after sex for an hour?

No. Viable sperm make their way although way up to the fallopian tube within 15 minutes of sex and lying down afterwards won’t change a thing.

Do we have to avoid lubricants when trying to conceive?

Not necessarily. There are some lubricants that may decrease sperm quality, such as typical water-based lubricants (K-Y or Astroglide brands). You may use a fertility-specific lubricant such as PreSeed, though. For a simpler option, both mineral oil and canola oil have shown no problems with sperm in studies, and so these seem likely to be safe for use when trying to conceive.

What else can I do to increase my chances?

There are a few habits you can change to increase your chances of conceiving. First and foremost, we encourage our patients to quit smoking. Women who smoke cigarettes have up to 60% increased risk of infertility, compared to similarly aged non-smokers. Of course, smoking has lots of ill effects on pregnancy development and growth, too, so stopping before pregnancy is ideal. Similarly, women who have more than two alcoholic drinks each day may also have decreased fertility, but the data on this is a little less clear than smoking.

Caffeine use appears okay, up to a point. Probably more than 2 cups of coffee or soda per day is too much, and may start to decrease fertility a little. If you’re into energy drinks, the caffeine content can vary widely between products, so check the side of your bottle/can and try to limit this to under 200 mg per day.

Maintaining a healthy body weight can also improve chances of conceiving. Women who are overweight are at increased risk of infertility, but so are women who are underweight. Overweight women may produce too much estrogen, interfering with ovulation and the uterine lining’s response to implantation. But very underweight women may also ovulate infrequently as their bodies think that resources are scarce and wasting energy on ovulation and pregnancy may not be best for her. So, maintaining a healthy weight can be important to maximizing fertility.

What about chemicals in the environment?

There is lots of active research into the effects of hormone modulating substances we encounter in our environment, whether they be harsh exposures like those who work with pesticides or dry cleaning products, or more subtle exposures like BPA in plastics. A lot of the real clinical understanding of exactly how these exposures may affect your ability to conceive is still uncertain. Many of the studies suggesting toxicity and fertility impairment are done in animals, and these are hard to generalize to human exposures at lower levels.


  • Frequent intercourse, daily or every other day, between menstrual days 7 and ovulation probably gives the best chances of conception.
  • Tracking ovulation may be helpful through using menstrual tracking app, cervical mucus changes, and/or ovulation predictor kits.
  • No certain position is better, nor is lying down after sex necessary.
  • Avoid smoking, excess alcohol and caffeine use.
  • If using a lubricant, consider mineral or canola oil, or a fertility specific brand such as PreSeed.
  • Maintain a healthy body weight.
  • See your doctor if you’ve not conceived after 12 months of trying. Shorten this to 6 months for women over 35.

Source: American Society of Reproductive Medicine, “Optimizing natural fertility: a committee opinion” Fertility and Sterility® Vol. 107, No. 1, January 2017, pp 52-58.

Cory Miller, MD, is board-certified in obstetrics and gynecology. He is a member of BJC Medical Group and affiliated with Progress West Hospital. Dr. Miller practices in O’Fallon, MO, and can be reached at 636-344-1073.  

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