When you’re pregnant, you must gain a certain amount of weight in order to support your growing baby. Some of this weight gain is the baby, while other parts are the placenta, extra blood and fat reserves for feeding after the baby is born. When you are carrying twins, proper weight gain becomes even more important, and you have to gain more than you would if you were carrying just one baby.

How Much to Gain

A woman pregnant with a single baby should gain around 25 to 35 lbs during her pregnancy. Women with twins should gain about 10 lbs more — between 35 and 45 lbs. However, this is just the recommended amount for an average-size woman. If you were underweight when you became pregnant, you should aim to gain more, and if you were overweight, you should aim to gain less. Talk to your doctor about the actual weight gain goal for your body.

Weight Gain Time Line

It’s particularly important for women pregnant with twins to gain weight early on in the pregnancy because there is a higher chance of pre-term birth. According to Family Education, you should gain about 5 to 10 lbs in the first trimester, then 1 to 1.5 lbs per week after that.

Eating for Weight Gain

MayoClinic.com suggests that in order to gain the right amount of weight for a twin pregnancy, you may need to eat as many as 2,700 calories per day. This doesn’t mean that you have the freedom to down an entire bag of potato chips, though. It’s important to eat healthy foods to meet your caloric goals. In particular, look for foods that are high in folic acid, iron, calcium and protein.

Emotional Issues

Whether you started out underweight, overweight or at a normal weight, the thought of gaining so much weight can be difficult to deal with. Focus on what you are doing for your babies rather than what’s happening to your body. Remember that all of this weight isn’t fat — when you stick to the recommended weight gain, much of the weight will naturally come off within a few weeks, since it’s just extra blood, a bigger uterus, the placenta and the babies themselves.

The Dangers of Not Enough

If you’re worried about what your body is going to look like after having your babies, it can be tempting to try to gain the minimum amount possible. Unfortunately, this could harm your babies. If you don’t gain enough weight, your babies may be underweight at birth, which is particularly dangerous since there is such a high chance that they’ll be born early.