Pregnancy and Weight Control

A mother's pre-pregnancy weight and how much weight she gains during pregnancy both have a major effect on the size of her baby. While having too large a baby increases the baby's risk of becoming obese, it is equally important to reduce the risk of a low birth-weight infant. Too low a birth weight (less than 5 1/2 lbs) increases the risk of birth defects and other health problems. The optimal birth weight is now considered to be 7-10 lbs. Generally, the lower the weight gain in pregnancy, the lower the birth weight. This is true for all women - even overweight women. Underweight women need to gain the most weight during pregnancy and obese women the least.

• Ideal weight gain. A total weight gain of 25-35 lbs during pregnancy is desirable. Normally, only 3-6 lbs is gained in the first trimester (12 weeks). Thereafter, an average of 0.8lbs each week is normal.
  
  
• Excessive weight gain. Weight gain of over 35 lbs during pregnancy may result in too large a baby. A sudden increase in weight might result from toxemia or excess calorie intake. Dietary changes to control weight gains are best supervised by an obstetrician and dietitian. Pregnancy is not the time for extreme dieting as fetal growth can be impaired.
  
  
• Inadequate weight gain. Weight gain of less than 15 lbs is more likely to result in a low birth-weight baby. The past practice of over-restricting food intake to limit weight gains is no longer considered healthy for pregnant women. Too little weight gain, even in obese women, indicates that the dietary intake is too low to provide adequate nutrition for optimal development of the growing baby and the maintenance of mother's health.
  
  
• Teenagers are a high risk group for low birth-weight infants. Unlike older mothers, growing teenagers may need to “eat for two”. A weight gain of 30-35 lbs will minimize the risk of a teenager having a low birth-weight baby. Under no circumstances should a growing teenager view pregnancy as a time to lose weight.
  

Only 4 lbs of the total weight gain is due to the developing baby. The remainder is comprised of vital tissues and fluids that nourish and protect the fetus before and after birth. The components of weight gain are:

The fat stores that the expectant mother lays down during pregnancy have important roles. For example, they act as a safeguard against any periods of food shortage. The energy stored in the fat is also used in producing breast-milk. Additionally, body fat insulates and protects the growing baby. The fat stores of 4-9 lbs represent approximately 25,000 calories and can subsidize the extra metabolic needs of late pregnancy and breast feeding. These fat stores may not be fully used and this may contribute to residual weight gain after each pregnancy.

You don't need that many extra calories during pregnancy; 100-300 calories each day is usually enough. That translates to, for example, one large banana (100 calories), two crackers and cheese (200 calories), a small chicken sandwich (300 calories).

However, calorie needs vary considerably from person. For women who substantially reduce their exercise while pregnant, the need for extra calories may be minimal. Even towards the end of the pregnancy only 2400 calories are needed daily by the average woman (taking 2100 calories as the needs of the average non-pregnant woman).

While few extra calories are required during pregnancy, there is a greater demand for extra nutrients. It is important to choose nutrient-dense foods and to avoid high fat and calorie-dense foods such as cookies, confectionery and soft drinks.

Vitamin/mineral supplementation, particularly of iron, folic acid and zinc is usually prescribed as a safeguard.

Pregnancy is not a good time to attempt weight loss, as the health of the growing fetus is placed at risk.

• Inadequate energy intake could “starve” the fetus of nutrients, especially in the third trimester, and increase the risk of a low birth weight baby.
  
• Excessive weight loss can produce ketones, a by-product of fat breakdown that may be detrimental to the baby's development.
  
• The mother runs the risk of ill-health both during pregnancy and in subsequent years. For example, inadequate calcium will increase the risk of osteoporosis (brittle bones) in later years.
  
• Unbalanced nutrition during pregnancy can severely affect milk production during lactation. Adequate protein and energy is required for optimal growth of the mammary glands. Even adequate nutrition during lactation may not overcome the lack of mammary gland growth that occurred during pregnancy.

Healthy eating habits acquired during pregnancy and breast feeding can form the basis of any necessary weight loss program after the birth of the baby. If a mother breast feeds her baby for at least 4-6 months, she will find that by 12 months her weight should return to pre-pregnancy levels.

Moderate exercise during pregnancy is beneficial. Swimming and walking are excellent forms of physical activity that are unlikely to overstress the body. Very strenuous activity is not advised as it may divert oxygen from the fetus to the exercising muscles. Lifting and carrying heavy objects should also be avoided. If any health problem is present, do not exercise without medical advice.

During pregnancy extra iron is required for the increase in mother's blood volume and for normal growth of the fetus and placenta. Since it can be difficult to get the recommended amounts of iron from food, a daily supplement is prescribed during the 2nd and 3rd trimesters. The extra iron promotes adequate stores in the mother to be used in breast feeding.

Folate is required for the production of new cells in the fetus and placenta. A folate supplement is usually given in conjunction with iron.

Excess alcohol can deplete the body of essential nutrients and can also cause defects in the fetus and lead to fetal alcohol syndrome. It is strongly advised to abstain from alcohol during pregnancy.

Cigarette smoking can constrict blood vessels supplying the placenta and reduce the nutrient supply to the growing baby. Smoking will also reduce oxygen supply to the developing baby and harm his or her health. Do not smoke while pregnant.