Scientific Benefits of Breastfeeding and Childbearing

Mrs. Parunak at Pursuing Titus 2 has a fascinating blog post about the health benefits of childbearing and breastfeeding. I've always heard that the more children a woman has, and the longer a woman breastfeeds are both beneficial to her health, but I've never really heard much of the "science" behind it. Being that I love learning new things, I was very interested to read about it! Here's a basic summary, but for more detail, be sure to check out "Telling the Truth About Birth Control" at Pursuing Titus 2! This will seem lengthy, but its really worth reading!

A 2002 article in New Scientist proclaimed that modern women in the UK were facing breast cancer rates as high as those of childless nuns in the nineteenth century and said,

Western women could reduce their breast cancer risk by nearly 60 per cent if they returned to pre-industrial levels of fertility and breastfeeding….For each child a woman has, her risk of the disease declines by 7.0 per cent. On top of this, for every year that she breast feeds, her risk declines by 4.3 per cent.

So how does this work? Why would a “return to pre-industrial fertility” help save women’s lives? Why is it that any decrease in childbearing, or postponement of childbearing increases your breast cancer risk? It’s because estrogen itself is a carcinogen. Every month a woman has a menstrual cycle, she is exposing herself to estrogen. That’s dangerous any time it happens, but it’s worse if she hasn’t had a full term pregnancy yet. This is why delaying childbearing “until you and your husband have gotten to know each other,” or “until you get your career established,” is actually risky business. The earlier you have your first baby, the lower your breast cancer risk. According to Daniel B. Kopans, M.D., Director of the Breast Imaging Center at Massachusetts General Hospital,

…a woman who has her first full-term pregnancy by the age of 18 has about one-third the risk of developing breast cancer as a woman who has her first full-term pregnancy after age 30.

When a girl reaches puberty, her breasts start to develop, but they don’t actually finish developing until she begins making milk for her first baby. The immature breasts of a woman who has not yet gone through pregnancy and breastfeeding are composed of type 1 and 2 lobules. (A lobule is a milk duct and several milk producing glands around it.) In fact, 70% of this woman’s breast tissue is type 1. Type 1 lobules are the most susceptible to breast cancer. 80% of breast cancers are formed in Type 1 lobules. 10% form in type 2 lobules. When women reach the last eight weeks of their first full term pregnancy, at least 70% of their breast tissue matures to type 3 lobules, and then when they begin nursing, their breasts fill with milk and become type 4 lobules. Type 3 and 4 lobules are cancer resistant. The sooner a woman’s breast tissue matures to type 3 and 4 lobules, the safer she will be from breast cancer because she will have exposed her cancer-vulnerable, immature breasts to fewer menstrual cycles, and therefore fewer onslaughts of estrogen. And the more babies she has, the more lobules will mature. (For more information, click here and read the excellent FAQ.)

But not only do many women delay and/or decrease childbearing, they do so through hormonal contraception (like the Pill), which contains steroidal estrogen. And while it is claimed that estrogen given with progesterone (as it always is in hormonal birth control) is not dangerous, there have been numerous studies linking hormonal contraception with increased breast cancer risk. A Mayo clinic meta-analysis of 23 studies found that 21implied increased risk, and combining the studies gave an estimated 44% increase in pre-menopausal breast cancer risk in women who used the Pill before their first full term pregnancy. The World Health Organization, in its own studies, found the risk to be slightly lower (24%), but still high enough to be scary, to me anyway. (Read more here. Click on “Girls on Steroids”)

The Lord never ceases to amaze me! Its incredible the way that He designed our bodies to naturally be protected just by following His blessing of "be fruitful and multiply"!