Overweight and pregnant

New research has suggested that babies born to obese moms have a higher risk of asthma and it’s the latest in a long line of studies pointing to the risks that can be associated with being overweight or obese during pregnancy.

Starting your pregnancy at a healthy weight and gaining the right amount during pregnancy is critical to giving your baby a healthy start in life – but it’s thought that almost half of pregnant women (including those who are already overweight) gain more weight than they should during pregnancy. Being overweight and pregnant can have serious health consequences for you and your baby because carrying too much weight while pregnant puts you at higher risk of developing high blood pressure (which in turn raises the risk of pre-eclampsia) and gestational diabetes, and miscarriage.

You’re also more likely to have labor complications that mean you need a cesarean delivery. These all put your baby’s health and wellbeing at risk.

How does fat harm your baby?

Fat may directly harm your unborn baby because those extra pounds don’t just sit there doing nothing. Fat cells are active, producing proteins called cytokines, which cause inflammation in the body. So fat goes beyond looking unpleasant – it also results in systemic inflammation that may affect your baby’s immune system and his lungs – here’s where the link with asthma comes in. And being overweight also can have indirect effects on your baby. It will make it more difficult for your caregivers to monitor his health and wellbeing and will make it more difficult for you to deliver him if you are too large to stay active during your labor.

Babies born to overweight and obese moms also are at increased risk of preterm birth. This is the leading cause of newborn death, and babies who survive preterm birth often face lifetime health challenges, such as breathing problems and mental retardation. Even babies born just a few weeks too soon have higher rates of death and disability than full-term babies and often need long periods of special care in a neonatal intensive care unit (NICU). They also are more susceptible to certain birth defects, especially neural tube defects such as spina bifida.

Studies also show that if you’re an overweight or obese mom-to-be this can affect your baby’s weight as he grows – children born to women who match or exceed the guidelines for pregnancy weight gain are four times as likely to be overweight at three years old and are more likely to develop high blood pressure.

How much weight should you gain?

Until recently, American College of Obstetricians and Gynecologists (ACOG) guidelines stated regardless of how much a mom-to-be weighed before she became pregnant, gaining between 26 and 35 pounds during her pregnancy could improve the outcome of pregnancy and reduce the risk of fetal death. The Institute of Medicine (IOM) recommended that overweight women should gain about 15 pounds during pregnancy.

The new guidelines are based on a study that followed 232 obese pregnant women, all of whom had a body mass index (BMI) of 30 or greater. Half of the women followed conventional prenatal nutritional guidelines and ate according to their appetite; the other half were placed on a well-balanced, nutritionally monitored program. The average weight gain in the eat-to-appetite group was 31 pounds, compared to 11 pounds in the managed group.

The findings showed that there were no fetal deaths, no growth-restricted babies and fewer babies weighing more than 10 pounds (which puts both baby and mom at risk) in the managed group. Women in this group gained less weight, had fewer cesarean deliveries, were less likely to develop gestational diabetes, and retained less weight after they had their babies than the women in the eat-to-appetite group.

With this in mind, the IOM now recommends that obese women – those with a body mass index of 30 or more – limit their weight gain to 11 to 20 pounds over nine months. The recommendations for women with a BMI of less than 30 remain the same, with overweight women (BMI 25 to 29.9) advised to gain 15 to 25 pounds over nine months, while underweight women (BMI less than 18.5) should gain 28 to 40 pounds, and normal-weight women (BMI 18.6 to 24.9) should gain 25 to 35 pounds.

Staying on track with weight gain

Your best bet for avoiding excess weight gain in pregnancy is to stick to a healthful diet that incorporates plenty of fresh fruits and vegetables, whole grains, lean meat, poultry and fish, and healthy fats. Avoid eating for two – you don’t need to consume any additional calories during your first trimester (weeks 0-12) and only need about 300 additional calories per day (for example, a yogurt teamed with a banana or a slice of toast) in the second (weeks 13-28) and third (weeks 29-40) trimesters (300 calories – mean, for example, a small jar of yogurt and banana).

Another recent study confirms this, showing that pregnant women who consume extra calories, as well as fried foods and dairy products, were more likely to gain more weight than is recommended during pregnancy. In the study, eating an extra 500 calories a day (about equivalent to a cream cheese bagel or a jumbo muffin) increased the odds of gaining too much weight by 10 percent and women who ate just one serving of fried food a day were four times as likely to gain too much weight.

Conversely, pregnant women with vegetarian diets in early pregnancy were half as likely to gain an unhealthy amount of weight, and those who exercised vigorously for a half hour a day reduced their risk by 20 percent. The researchers also found that consuming more monounsaturated fat, found in olive oil and nuts, was linked with a lower risk of excessive weight gain.

Check out gurgle’s advice on healthful eating in pregnancy, pregnancy without the pounds, and exercise in pregnancy to keep you and your unborn baby well-nourished and fit.

The information in this feature is intended for educational purposes only. If you have any concerns about your health, the health of your child or the health of someone you know, please consult with a doctor or other healthcare professional.

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Last Modified: 07/06/2009

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