Weight in pregnancy best controlled by diet, study shows

Pregnant women, including those who are obese or overweight, should be encouraged to minimise weight gain through diet, according to major new research from Queen Mary, University of London.

Piling on excess weight during pregnancy increases the risk of complications for pregnant women but doctors have been cautious in advising women on ways to manage weight for fear of any adverse effect on mother or baby.

However, the new study published in the BMJ shows that following a healthy diet, overseen by health professionals, stems excess weight gain in pregnancy and reduces the risk of pregnancy complications such as pre-eclampsia, diabetes, high blood pressure and early delivery.

Half the UK population are either overweight or obese and the rates are rising. Around a third of women gain more than the recommended amount during pregnancy.

Previous research has linked obesity during pregnancy with an increase in a variety of risks including high blood pressure, diabetes, miscarriage, birth defects, blood clots, pre-eclampsia, and even maternal and infant deaths.

The new research, which brings together the results of 44 separate studies, is the largest of its kind and includes data on more than 7,000 women. It was commissioned and funded by the NIHR's Health Technology Assessment programme.

The researchers investigated the effect of diet, exercise, or a combination of the two. They looked at how much weight women gained throughout pregnancy and whether mother or child suffered from any complications.

Pregnancy and Weight Gain Gaining the right amount of weight during pregnancy by eating a healthy, balanced diet is a good sign that your baby is getting all the nutrients he or she needs and is growing at a healthy rate. It is not necessary to "eat for two" during pregnancy. It's true that you need extra calories from nutrient-rich foods to help your baby grow, but you generally need to consume only 100 to 300 more calories than you did before you became pregnant to meet the needs of your growing baby.

Ask your health care provider how much weight you should gain during pregnancy. A woman of average weight before pregnancy should gain 25 to 35 pounds during pregnancy. Underweight women should gain 28-40 pounds during pregnancy. Overweight women may need to gain only 15-25 pounds during pregnancy. You may need to gain more or less weight, depending on what your health care provider recommends.

In general, you should gain about 2 to 4 pounds during your first three months of pregnancy and 1 pound a week for the remainder of your pregnancy. If you are expecting twins you should gain 35 to 45 pounds during your pregnancy. This would be an average of 1 ½ pounds per week after the usual weight gain in the first three months.

Although all three methods reduced the mother's weight gain, diet had the greatest effect with an average reduction of nearly four kilograms. Exercise only resulted in an average reduction in weight gain of just 0.7kg. A combination of diet and exercise only produced and average reduction of one kilogram.