If you’re thinking about having a baby anytime soon, now is when you want to lose those extra pounds — or gain a few if you’re underweight.
“Many women don’t understand that keeping their weight within normal range helps them ovulate regularly,” said Dr. Sandra Carson, vice president of education for the American Congress of Obstetricians and Gynecologists (ACOG). And anything that interferes with regular ovulation could make it harder to get pregnant.
A recent study from the Center for Cardiovascular and Metabolic Research at the University of Hull in England suggests why overweight women might have more trouble conceiving: Their eggs are smaller, and therefore less likely to complete development post-fertilization.
The researchers, led by Dr. Roger Sturmey, looked at excess embryos that were created during in vitro fertilization but not implanted. They found that those embryos of overweight women that do develop reach the morula stage (the first stage of embryonic development after the fertilized egg starts dividing and multiplying) faster than embryos of women who are not overweight. However, the resulting blastocyst (the next stage of development, which begins about five days after fertilization) contains fewer cells, especially in the outermost layer known as the trophectoderm, which forms a large part of the placenta.
The study, published this month in the journal Human Reproduction, was small, but the “observed changes could indicate long-term implications for the health of the offspring of overweight and obese women,” the paper concluded.
Once you get pregnant, carrying excess weight is also associated with a higher risk of complications for both the mother-to-be and her offspring. According to ACOG, these include:
*Hypertension (high blood pressure)
*Gestational diabetes
*Pre-eclampsia (a dangerous condition characterized by hypertension and protein in the urine)
*Macrosomia (a larger-than-normal baby)
*Preterm birth
*Birth injury
*Cesarean section
*Birth defects, especially neural-tube defects like spina bifida and anencephaly.
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In addition, if you have too much body fat, it could make it harder for your doctor to monitor your baby with ultrasound and to hear its heartbeat.
Being underweight isn’t good either, experts agree. It increases the risk of having a premature delivery or a low-birth-weight baby, who could have problems both during labor and after birth.
According to Dr. Ranit Mishori of Georgetown University School of Medicine in Washington, the time to conception for obese women is twice as long as that for normal-weight women. Underweight women, on average, take four times as long as their normal-weight peers to get pregnant.
ACOG recommends that women check their body-mass index, or BMI, to figure out if they’re overweight, underweight or just right. You can find your BMI using an online calculator.
Having a BMI of less than 18.5 is underweight; 18.5-24.9 is considered normal; 25-29.9 is overweight; and 30 or higher is obese.