March 15, 2012

Delivering Small Full-Term Babies Puts Moms at Risk

(Ivanhoe Newswire) — Small for their gestational age, infants account for approximately 10 percent of births, and increased maternal risk for ischemic heart disease in women. Until now, researchers believed any link was due to common genetic or environmental factors or to overall poor health, but a new study is shedding new light.

"What we found instead is that pregnancies that produce SGA infants may trigger long-term cardiovascular changes that increase the mothers' risks for heart disease," Dr. Radek Bukowski, professor of obstetrics and gynecology in the Division of Maternal-Fetal Medicine at UTMB, was quoted saying. "If future research confirms birth weight as a solid predictor, we will have a low-cost, effective method to improve identification of women at risk and potentially help prevent heart disease decades before women experience trouble."

The researchers analyzed a nationally representative sample of more than 6,600 women who participated in The National Health and Nutrition Examination Survey (NHANES) between 1999 and 2006. SGA was self-reported and defined as giving birth at or after 37 weeks of gestation to an infant weighing less than five pounds, eight ounces (2,500 grams).

The survey collected information about the women's own history of IHD, stroke, hypertension, diabetes and cancer; family histories of the same disorders; IHD risk factors, including: race and ethnicity, education, marital status, income, smoking status, alcohol use, dietary fiber intake, body mass index, activity levels and triglyceride and cholesterol levels; and age at time of last birth and at IHD diagnosis.

The relative odds for IHD were almost two-fold higher (9.6 percent versus 5.7 percent) in women who delivered a SGA infant. Further, having a SGA baby was as strong a risk factor as having hypertension or diabetes.

While cautioning that any explanation for this effect is speculative at this point, Bukowski suggested it could be due to low concentrations of angiogenic factors (which stimulate blood vessel growth and repair), such as placental growth factor in maternal circulation. Placental growth factor has been shown to stimulate blood-vessel development and repair in the heart; a deficiency could decrease this process and permanently affect coronary circulation, resulting in IHD later in life.

This possibility is supported by studies that have shown that preeclampsia, a placental disorder during pregnancy that is also associated with SGA, results in impaired vascular function and increases the risk of future hypertension and heart disease.

"SGA deliveries could allow for early intervention and prevention for heart disease. If this link is proven, doctors could look out for women who deliver smaller than average babies and provide education and preventative care, which would be especially important in resource-poor countries," Dr. Bukowski was quoted saying. "It could also be used years after childbirth, as most women remember their babies' birth weight quite accurately."

SOURCE: PLos, March, 2012