Birthing Big Babies Increases Risk of Breast Cancer

By Kai Colvin - Senior Medical Research Editor | October 1st, 2012

The average size of a healthy, full-term newborn is 7.5 pounds. According to a study published in, PLOS ONE, delivering an infant greater than 8 pounds more than doubles the risk of breast cancer.

Researchers from the University of Texas Medical Branch at Galveston advise that birthing a big baby is linked with a hormonal milieu that favors breast cancer development and progression.

The study, led by Dr. Bukowski, professor of obstetrics and gynecology in the Division of Maternal-Fetal Medicine, bodies an amassing indication that a woman's own birth weight and her children’s weight are linked to breast cancer was illustrated by two examinations of distinct data studies:

Framingham Offspring Birth History Study—generations of women’s medical examinations and laboratory assessments between 1991 and 2008.

**Lead researcher, Dr. Bukowski and his team studied 410 women’s statistics including the maternal birth weight, infant birth weight and results of later examinations to determine breast cancer risk. The researchers examined data from the study on known breast cancer risk factors, such as age, ethnicity, BMI, and diabetes, use of hormone replacement therapy and maternal history of the disease. Roughly 7.6 percent of the women from Framingham study were later diagnosed with breast cancer.

First and Second Trimester Evaluation of Risk for Aneuploidy (FASTER) Trial— trial indicated pregnancy hormones in nearly 24,000 women at 15 US clinics between 1999 and 2003.

**Lead researcher, Dr. Bukowski and his team studied assessments of the hormones that affected infant birth weight and breast cancer risk (estriol, anti-estrogen alpha-fetoprotein (AFP) and pregnancy-associated plasma protein-A).

“We also found that women delivering large babies -- those in the top quintile of this study, which included babies whose weight was 8.25 or more pounds -- have increased levels of hormones that create a 'pro-carcinogenic environment.' This means that they have high levels of estrogen, low levels of anti-estrogen and the presence of free insulin-like growth factors associated with breast cancer development and progression," stated Dr. Bukowski.

He further added, “Women can't alter their pregnancy hormones, but can take steps to increase their general protection against breast cancer.”

Understanding the Risks

Risks of having large babies include:

Diabetes during pregnancy
Excessive weight gain during pregnancy
Obesity

If you are pregnant, you should discuss with your doctor how much weight you should gain during your pregnancy.

Maintaining a normal weight, breastfeeding, having more than one child, following a healthy diet and exercising have been shown to reduce overall cancer risks.

To learn more about pregnancy, find an OBGYN in your area.