Pregnant U.S. Women Routinely Gain
Too Much Weight

The CDC reports in its Morbidity and Mortality Weekly Report that more than two-thirds of pregnant women in the U.S. either gain too much or too little weight during pregnancy, with gestational weight gain being the far more prevalent problem.

In the study, 20% of pregnant women gained less than the recommended amount of weight, and 48% gained more than the recommended amount. However, the American College of Obstetricians and Gynecologists (ACOG) reports that more than half of pregnant women in the U.S. are overweight or obese. In any case, fewer than one-third (just 32%) of women had gestational weight gain within Institute of Medicine recommendations. Women who were overweight or obese before pregnancy had the highest prevalence of excessive gain, the researchers note.

Health implications
The weight a woman gains during pregnancy has important health implications for both mother and child. The high prevalence of excessive weight gain, which varies with pre-pregnancy BMI, is of concern because excessive gain increases the risk for fetal macrosomia, which is defined by any baby weighing more than 8 lbs 13 oz. (and so “significantly larger than average”).

Postpartum weight retention is another risk of too much gestational weight gain, which naturally can lead to obesity in mothers—and possibly children. It has been observed before that postpartum sleep deprivation and depression are also associated with postpartum weight retention. In addition to promoting obesity and possibly depression and sleeplessness, post-partum retention, as we shall see below, is of particular concern for another reason.

Gain between pregnancies
A Lancet study has found that women who gain weight between pregnancies have an increased risk for adverse birth outcomes. The researchers looked at over 450,000 women who delivered children from 1992 through 2012.

Stillbirth occurred in 2.4 out of 1,000 second births, with risk in the second pregnancy increasing linearly with higher BMI between pregnancies. Infant and neonatal mortality occurred overall in 2.1 per 1,000, and 1.2 per 1,000, respectively. Compared with women whose weight remained stable, those who gained 2 to 4 BMI units by the second pregnancy had a 38% increased risk for stillbirth, and those who gained 4 or more BMI units had a 55% increased risk.

Gestational weight gain recommendations
The IOM provides recommendations promoting good health during pregnancy specific to a woman's BMI prior to pregnancy. ACOG supports the guidelines, which are as follows:

  • Those with a pre-pregnancy BMI under 18.5 should gain 28–40 pounds.
  • Normal-weight women (BMI, 18.5–24.9) should aim for 25–35.
  • Overweight women (BMI, 25–29.9) should aim for 15–25.
  • Obese women (BMI, 30 or more) should gain only 11–20.

For access to great tools including a Pregnancy Weight Tracker, a Recommended Weight Gain by BMI chart, and a BMI Calculator, visit IOM Healthy Weight Gain During Pregnancy.

Exercise is indicated
A committee opinion from ACOG suggests that women with uncomplicated pregnancies should aim for 20 to 30 minutes of moderate-intensity physical activity most days.

The risks of exercise in pregnancy are minimal. On the contrary, there is plenty of evidence and great consensus now that the changes produced during exercise are helpful to pregnancy. Exercise increases blood volume, both in circulation and for each beat pumped, improving the body's ability to deliver oxygen to tissues, which in turn greatly benefits your baby. And benefits to overweight women include reduced risk for gestational diabetes.

Discuss exercise with your doctor before embarking on an aerobic regimen during pregnancy, as there are a few contraindications to exercise during pregnancy, and your overall physical health needs to be assessed if you’ve been previously sedentary. Yet for women with complicated pregnancies, the committee says that bed rest “is only rarely indicated.”

Regular, vigorous exercise throughout early pregnancy does not increase the incidence of miscarriage or birth defects. Workplace stress such as standing hours on end or frequent heavy lifting are not recommended during pregnancy, but this is a far cry from even vigorous recreational exercise such as running.

Birthing a better baby?
For exercised babies, all aspects of fetal growth and development after birth have been shown to be equal to or better than non-exercised babies. Neither starting an exercise regimen nor continuing one results in preterm labor. Neither results in decreased fetal growth either—just decreased fetal fat, which does not result in low body temperatures as was once thought.

Also, the blood glucose of these less plump infants is perfectly normal. What's more, babies of pregnant exercisers tend to be easier to care for. They sleep through the night earlier, do not typically have colic and often self-quiet. Blind evaluations of exercised and non-exercised babies repeatedly show exercised babies need less consolation when disturbed.

Use common sense
Exercise enthusiast and obstetrician James F. Clapp III points out in his compendium of exercise advice for pregnant women that if it feels good, it's probably okay. Obviously, avoid any sport with the risk of projectile trauma. Also best avoided are high altitudes, scuba diving and competition in general. But even bouncing on a trampoline with proper back support is fine if there is no discomfort. Proper attention to discomfort, particularly abdominal or pelvic pain, is as important as the exercise itself. If this occurs, do not continue until the situation is clarified by your doctor.

The big four contraindications to exercise are:

  • Injury
  • Disease
  • Pain
  • Bleeding

Also, take care to avoid low blood sugar and never ignore fatigue.

CDC, MMWR, “Gestational Weight Gain—United States, 2012 and 2013,” 2015, Vol. 64, No. 43, pp. 1215-1220,

IOM, “Healthy Weight Gain During Pregnancy,”

ACOG, Committee on Obstetric Practice Opinion, “Weight Gain During Pregnancy,” No. 548, Reaffirmed 2015,

The Lancet, Dec. 2, 2015, Published Online,

Exercising Through Your Pregnancy by James F. Clapp III, MD, 2002, Addicus Books, Omaha, NE

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