You've probably heard of some couple who struggled with fertility for year, but then had no struggles after their first baby arrived. I was one of those people. At 23 years old my doctor told me getting pregnant would be mostly impossible due to a reproductive disease. After having surgery to deal with the diagnosis, I got pregnant within months. . . and then again months after my first child was born. As unlikely as it sounds, my story is not unique. When this happens to women, many wonder are you more likely to get pregnant after having a baby? It turns out there are some pretty convincing theories about this anecdotal phenomenon.
The first theory has to do with the reproductive disease I have, called endometriosis. Endometriosis affects 176 million women worldwide, and one in 10 women in the U.S., according to The Endometriosis Foundation of America. Symptoms of endometriosis, which include include: "killer" cramps that don't go away using medication and impede daily life, heavy flow, bowel and urinary issues, painful ovulation, pain during sex, and infertility, can show up as early as 12 years of age. The disease is still not totally understood, but as explained on the aforementioned website, endometrium tissue (similar to what is found in the uterus) grows in other parts of the body and most often, in the pelvic area. Some women who don't have severe symptoms or who have been dismissed by doctors, don't even know they have it until they try to get pregnant.
As reported in How Stuff Works, fertility treatments can overcome undiagnosed endometriosis in some cases and keep it at bay temporarily. Dr. Sunny Jun with Colorado Center for Reproductive Medicine (CCRM) in San Francisco was quoted in the piece saying:
Basically, women don't get their period while they're pregnant, so the endometriosis - diagnosed or not - clears up and makes her more likely to conceive.
The next theory has to do with your stress levels. I almost cringe typing this because the "just relax" phrase can be so insulting to people going through fertility struggles. If "just relaxing" was really the key to having babies, doctors would be prescribing trips to the Caribbean so couples could get pregnant. Fertility issues are so much more complicated than stress alone, however, there does appear to be a link.
According to an article in Parents, chronic stress can affect ovulation in some women by altering signals to the hypothalamus. This is the area of the brain that regulates some of the hormones that trigger the ovaries to release eggs each month. Basically, if a woman's menstrual cycle is seeing a change because of stress, it's likely to impact her fertility. In the same article, it was also noted that some research shows stress may also impact testosterone levels and sperm production in men.
As the theory goes, you become less stressed after having a baby whether it's through your own biology, fertility treatments, or adoption because you have your baby. That's it, the stress of conceiving is over. "For some women, after having their first child, the pressure of becoming pregnant significantly subsides and with decreased stress and lack of contraception, natural pregnancies may occur," Jun explained, noting that there are no definitive studies showing stress directly impacts fertility, but decreasing stress in general can have positive outcomes.
Ultimately, there isn't solid data on the subject and much of the hypotheses are generalized ideas using a set of facts and principles that already exist in the medical field. There are no specific explanations regarding the ease of subsequent pregnancies. Sometimes, inexplicably, things simply line up. Even if there is no visible rhyme or reason, scientific or spiritual, the "miracle of life" is indeed, just that.