Obesity and Pregnancy

Everyone knows there are numerous health risks associated with being overweight or obese, but obesity during pregnancy carries additional risks that prospective mothers need to understand. Women who are significantly overweight during pregnancy have a much higher risk for diabetes, hypertension, and other complications that can affect the health of mother and baby alike, and they also have notably higher rates of miscarriage and stillbirth.

Obesity is widespread in the United States and in some parts of the developing world. According to a recent article in the New York Times, 36 percent of American women of childbearing age are overweight or obese, and the American College of Obstetricians and Gynecologists states that 8 percent are extremely obese.

Definition of Obesity

Body Mass Index (BMI) is a useful tool to help define obesity. It is calculated based on a person’s height and weight. Online BMI calculators are readily available. A BMI of 25 to 29.9 means a person is overweight. A BMI greater than 30 is the definition of obesity. For a woman who is 5 feet 5 inches tall for example, a BMI of 30 means she weighs 180 pounds.

Complications of Obesity During Pregnancy

In addition to the numerous ways in which obesity complicates the mother’s health directly, there are challenges involved in the care of women who are overweight and pregnant. Pregnancy ultrasound, for example, is less effective if the ultrasound waves used to produce the image have to penetrate thick abdominal fat.

C-section delivery is more common among overweight or obese mothers, and it is also riskier because surgical wounds take longer to heal in obese patients, and they are more likely to become infected. Higher doses of antibiotics are required for a C-section delivery if the patient is obese, and there is a greater risk of thrombosis, a dangerous condition that arises when a blood clot forms and blocks a blood vessel. C-section deliveries are also more complicated for overweight or obese women due to problems associated with anesthesia (see below), and those who have had a C-section delivery are less likely to be able to deliver vaginally in future pregnancies.

After childbirth, obese or severely overweight mothers are also prone to postpartum weight retention and breastfeeding problems. Studies have shown that obese women are less likely to initiate breastfeeding, and fewer than half of them sustain the practice for longer than six months. The problem is that such women produce less milk, and the milk they do produce takes longer to come in. This breastfeeding difficulty has two consequences: it compromises the baby’s nutrition, and it can cause the mother to retain more of her pregnancy weight gain than she otherwise might.

Other potential complications associated with obesity during pregnancy include:

  • Gestational diabetes
  • Hypertension
  • Preeclampsia—a potentially dangerous form of high blood pressure that affects pregnant women
  • Respiratory problems: Obese women are more likely to suffer from asthma, and 30 percent find that their asthma gets significantly worse during pregnancy.
  • Post-term pregnancy: Women who are overweight are more likely to remain pregnant after their due date.
  • Miscarriage
  • Stillbirth
  • Sleep apnea is common among overweight people, and pregnancy can make it worse.
  • Macrosomia: Women who are significantly overweight while pregnant have a greater chance of delivering an abnormally large baby. Such babies are more likely to be injured during childbirth, and more likely later to suffer childhood and adolescent obesity.
  • Urinary tract infections
  • Premature birth: Obese women are more likely to have labor induced early for medical reasons, although for reasons unknown their rate of spontaneous preterm labor is actually 20 percent lower than that of slimmer women.
  • Birth defects, particularly neural tube defects such as spina bifida and anencephaly. This may be due to undiagnosed diabetes at the time of conception.

Special Care for Women Who Are Overweight and Pregnant

Because ultrasound testing is less effective on people who are severely overweight, your doctor may delay the first ultrasound for a couple of weeks while the fetus grows larger, possibly waiting until the 20th or 22nd week of pregnancy in order to obtain a clearer image. He or she may also want to conduct an ultrasound test called a fetal echocardiography in order to check for the possibility of a congenital heart defect in the baby.

A normal pregnancy generally involves a standard test known as a glucose challenge test. This is done to screen for gestational diabetes, and the test is usually administered between the 24th and 28th week of pregnancy. If you are obese, however, your doctor may want to perform this test earlier, perhaps even during your first visit after the confirmation of your pregnancy. If the results of the test are normal, your doctor may still want to test you again later in your pregnancy.

Exercise while pregnant

While some amount of exercise is advisable for all pregnant women, it is especially important for overweight or obese pregnant women. No matter how inactive a woman is before pregnancy, she can still begin some type of exercise program during pregnancy. Walking or swimming are excellent exercises for those who are just starting out.

Begin with a 10–15 minute walk or swim, and do this every other day. After two weeks, add five minutes, and then every week or two, add five more minutes. The goal is one hour of brisk walking or swimming three times a week. This will have many benefits. It may help minimize pregnancy weight gain, can help prevent high blood pressure or gestational diabetes, and can help you just feel better, sleep better, and experience fewer of the typical pregnancy aches and pains that are experienced by nearly all pregnant women.

Obesity and Anesthesia

If emergency surgery becomes necessary, whether it be a C-section or some other procedure, obesity complicates anesthesia, especially for pregnant women. Determining the correct dosage of anesthesia is more difficult for obese patients, and epidural or spinal anesthesia is usually recommended. Unfortunately, these methods are also problematic because the patient’s thick layer of fat may obscure anatomical landmarks that the attending physician would normally use to correctly place the needle—and because simply getting the needle through the fat may be difficult.

Does Being Overweight Affect Fertility?

Obesity can have long-term effects on the body that lead to irregular ovulation and dramatically affect fertility. The success rate of in vitro fertilization can also be affected negatively by severe weight problems.

Bariatric Surgery and Pregnancy

More than 50,000 women have some type of weight-loss surgery each year, and while this type of surgery frequently improves the possible outcome of pregnancy for obese patients, women who have had this procedure are more likely to suffer deficiencies in iron, vitamin B12, folic acid, vitamin D, and calcium. Due to the rapid weight loss that tends to follow bariatric surgery, it is strongly recommended that any woman who has it waits at least a year before attempting to become pregnant.

Healthy Pregnancy Weight Gain

As noted above, women who have had bariatric surgery are at risk for certain vitamin deficiencies, but these same deficiencies are common among pregnant women in general. It is important to take steps to ensure that you obtain proper nutrition during your pregnancy, and your weight gain should be steady.

“Eating for two” does not mean eating enough food to sustain two adults. While you are pregnant, you should take in about 300 more calories per day than you normally would, the equivalent of half a sandwich and a glass of skim milk. The recommended pregnancy weight gain for a woman who is overweight or obese is 11 to 20 pounds if she is carrying one fetus, or 25 to 42 pounds if she is carrying twins or multiples.

Overweight and obese women need gain very little weight at all during pregnancy if they maintain a healthy diet and are active. Many heavy patients have very safe pregnancies and healthy babies and weigh nearly the same at the end of the pregnancy as when they started! And six weeks later, they weigh less than their pre-pregnancy weight. This is called “Dr. Jick’s pregnancy weight loss program!”

This page was last updated on 06/2017

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