Whether you're trying to get pregnant soon or planning to wait a decade, everyone should know the medical facts related to fertility. Here are 10 things that you may not know about the baby-making process, courtesy of the physicians at Pacific Fertility Center. 

1) Your fertility is mostly determined by genetics, which influences how many eggs you are born with.

At birth, women have about two million eggs in their ovaries. For every egg ovulated during your reproductive life, about 1,000 eggs undergo programmed cell death, so a woman’s supply of eggs is reducing over time. 

2) Regular menstrual cycles are a sign of regular ovulation.

Most women have regular cycles lasting between 24 and 35 days. This is usually a sign of regular, predictable ovulation. Women who do not ovulate regularly have irregular menstrual cycles. 

3) Basal temperature charting does not predict ovulation.

An older method of tracking ovulation involves taking your oral body temperature each morning before getting out of bed. The main problem with using this method is that your temperature rises after ovulation has already occurred. A better method is to use over-the-counter urine ovulation predictor test kits.

4) Most women with blocked fallopian tubes are completely unaware they may have had a prior pelvic infection.

About 10 percent of infertility cases are due to tubal disease, either complete blockage or pelvic scarring causing tubal malfunction. One major cause of tubal disease is a prior pelvic infection from a sexually transmitted disease such as chlamydia.

5) In most cases, stress does not cause infertility.

Except in rare cases of extreme physical or emotional distress, women will keep ovulating regularly. Conceiving while on vacation is likely less about relaxation than about coincidence and good timing of sex. 

6) By age 44, most women are infertile, even if they are still ovulating regularly.

Even with significant fertility treatment, rates of conception are very low after age 43. Most women who conceive beyond their mid-40s with fertility treatment are using donated eggs from younger women.  

7) Having fathered a pregnancy in the past does not guarantee fertility.

Sperm counts can change quite a bit with time, so never assume that a prior pregnancy guarantees fertile sperm. Obtaining a semen analysis is the only way to be sure the sperm are still healthy!

8) For the most part, diet has little or nothing to do with fertility.

Despite popular press, there is little scientific data showing that a particular diet or food promotes fertility.

9) Vitamin D may improve results of fertility treatments.

A recent study from the University of Southern California suggested that women who were undergoing fertility treatments, but had low vitamin D levels, might have lower rates of conception. This vitamin is also essential during pregnancy. At Pacific Fertility Center, we recommend our patients take 2,000-4,000 IU per day.

10) Being either underweight or overweight is clearly linked with lowered levels of fertility.

The evidence in recent years is that obesity is clearly linked with a longer time to conception. Having a body mass index (BMI) less than 18 or over 32 is associated with problems ovulating and conceiving.