A sensible guide to weight gain during pregnancy

Most women can expect to gain from 25 to 35 pounds during their pregnancy, but in general, notes Lisa Weston, registered midwife and vice president of the Association of Ontario Midwives, a woman’s weight gain during pregnancy is based on her pre-pregnancy body mass index (BMI): the higher your pre-pregnancy BMI, the less you should gain while pregnant, and vice versa. It’s a good idea to consult your doctor about your healthy body weight for each trimester.

Eating well

Throughout your entire pregnancy, your body needs extra calories, protein, minerals and vitamins. If you’re pregnant or trying to conceive, eat a balanced diet daily and choose a variety of foods from the four food groups’grain products, vegetables and fruit, milk products, and meat and alternatives. Choosing foods from each of these food groups will ensure your body has everything it needs to support a healthy pregnancy.

The first trimester

Most women gain 3 to 5 pounds during the first trimester. Some of this weight gain can be attributed to the extra fluids your body needs to sustain the baby’s life: increased maternal blood supply and amniotic fluid. Some women are plagued with nausea and morning sickness during this trimester, which may prevent them from gaining weight due to food; and in fact, some women with severe symptoms may even lose a few pounds.

The second trimester

It’s not surprising that most women gain weight slowly but steadily during the second trimester. Your waist begins to thicken and your abdomen expands to accommodate the growing fetus. Most women need to add maternity clothes to their wardrobe or borrow bigger sized clothing during the second trimester. Weight gain during this trimester can also be attributed to nausea and morning sickness symptoms abating, food aversions disappearing, and cravings increasing. Most women gain an average of 1 to 2 pounds a week during the second trimester.

The third trimester

The average weight gain of 1 to 2 pounds a week will continue into the third trimester. Your baby is going through a huge growth spurt, gaining fat and muscle during the final stages of your pregnancy.  By the time you give birth, Weston explains that most women will be carrying an extra 26 to 33 pounds, but your baby only contributes to a small portion of that extra weight, since the average baby weighs 7 1/2 to 8 1/2 lbs. The baby’s life support makes a difference, too: the placenta weighs 1 to 3 pounds and amniotic fluid weighs 2 pounds. Weight gain in pregnancy can also be attributed to the uterus (2 to 2 1/2 pounds), increased body fluids and blood volume (3 1/2 to 7 pounds), and the increased body fat and breast tissue (10 to 12 pounds) your body has saved for breastfeeding.