By Chris Woolston, M.S., and Melanie Haiken, M.J.
Putting on extra weight isn't usually a winning strategy for good health. But now that you're pregnant, you need to keep the needle on your scale moving in the right direction. No matter what type of body you have now, it needs to get bigger.
How much weight should I gain?
According to the March of Dimes, a woman who started pregnancy at a normal weight should expect to gain about 25 to 35 pounds over nine months. You can easily reach this goal by adding about 300 extra calories to your daily diet. If you were underweight when you conceived, you should gain between 28 to 40 pounds during pregnancy.
Overweight women should generally try to gain only 15 to 25 pounds, and obese women should aim for only an 11 to 20 pound weight gain. This is because excessive weight may put you and your baby at risk for medical complications. Whether you're carrying one baby or two, your doctor can help you find the target that's right for you.
What if I have twins?
If you're normal weight and carrying twins, the recommended weight gain is 37 to 54 pounds. If you're overweight, aim to gain between 31 and 50 pounds. And if you're obese, try to gain no more than 25 to 42 pounds during pregnancy.
How quickly should I be gaining weight?
If you started at a healthy weight, you should expect to gain from one to four and a half pounds in the first trimester. As your baby really starts growing, you will too. In the second and third trimesters, you can expect to gain about one pound a week. You can check your progress by using a weight gain chart such as the one provided by the March of Dimes on its Web site.
You'll need a different schedule if you were thin or overweight before pregnancy. If you were on the petite side, you should try to gain a little more than one pound a week during the second and third trimesters. If you were overweight, you don't need to gain any more than one to four and a half pounds in the first trimester. After that, you should be gaining slightly over a half pound a week in the second and third trimesters.
If you were obese when you got pregnant and gain between one and four and a half pounds in the first trimester, aim for about a half-pound (1/2 pound) every week in the second and third trimesters. It is important not to gain too much weight, but never try to lose weight while you are pregnant -- it could be harmful.
What else should I expect?
Women who have morning sickness often gain very little and even lose a pound or two in the first weeks of pregnancy. This loss is minor, and they often make up for it later on in the pregnancy. Of course, it's important for women to stay hydrated if they suffer from frequent bouts of morning sickness, so be sure to drink plenty of water.
Don't be alarmed if your weight gain doesn't follow a strict schedule. If you put on a little extra weight one week and a little less the next, you can still hit your overall target.
However, you should be concerned if you gain more than five pounds a week during the second half of pregnancy. This could be a sign of preeclampsia, a serious condition that could threaten both you and your baby. You should also contact your doctor or midwife if you don't gain any weight for more than two weeks between the fourth and eighth month of pregnancy.
Why do I need all that weight?
Your baby will weigh about seven pounds at birth, so you may be wondering where all of those other pounds go. Your placenta and amniotic fluid will each weigh about two pounds. (So far, that makes 11 pounds that you will lose immediately at birth.) You will also have two extra pounds of breast tissue, three extra pounds of blood, four extra pounds of other fluids, two extra pounds of uterine tissue, and seven pounds of extra fat. The fat will help keep your baby well-nourished during the pregnancy and give you reserves for breastfeeding..
What happens if I gain too much or too little weight?
There's a reason your healthcare provider will put you on the scale during every checkup. A healthy weight is a huge part of a healthy pregnancy. If you gain too much weight, you could increase your risk for complications such as high blood pressure and diabetes, and you may not be able to deliver your baby vaginally. You'll also be more likely to suffer varicose veins, backache, extreme tiredness, and leg pain.
You don't want to put on too little weight, either. If you fall short of your goal, your baby is more likely to be born underweight or premature.
Should I be concerned about how I'm going to lose the extra weight afterwards?
Try not to worry about it during your pregnancy. Remember, the baby accounts for much of the added weight; a typical newborn weighs in at 7 pounds. And the amniotic fluid, placenta, and extra body fluids and blood add up to another 10 pounds or so.
If you're planning to breastfeed, chances are you'll have less trouble losing the additional weight; nursing expends at least 500 additional calories each day. Exercise and a healthy diet are a great way to lose weight.
You also may find that getting used to following a healthy diet and exercising while pregnant makes it easier to continue that pattern once your baby's born. If you're gaining weight too fast and are worried about it, or if you discover once the baby's born that you can't seem to lose the added pounds, talk to your doctor or a dietitian who can evaluate your eating habits and help you make your calories count.
In the end, gaining the right amount of weight during pregnancy is a balancing act. You need to eat extra calories -- but not too many. And you'll want to stay active -- but not so active that you end up burning all of those extra calories. If you're having trouble staying on track, ask your doctor for advice. Remember, this is one time when your weight really matters to somebody else.
Weight Gain During Pregnancy. Centers for Disease Control and Prevention. Last updated October 14, 2016.
March of Dimes. Tracking Your Weight Gain. http://www.marchofdimes.com/pnhec/1808_1914.asp
Nemours Foundation. Obesity. http://www.kidshealth.org/
March of Dimes. Weigh to grow. http://www.marchofdimes.com/pnhec/159_153.asp
Weight Gain During Pregnancy: Rethinking the Guidelines. Institute of Medicine. 2009.
American Academy of Family Physicians. Preeclampsia. http://www.familydoctor.org/064.xml?printxml
La Leche League. How can I lose weight safely while breastfeeding? http://www.lalecheleague.org/FAQ/diet.html
Strong Health. Weight Loss. http://www.stronghealth.com/services/womenshealth/maternity/postpartumweightloss.cfm
March of Dimes. Weight Gain During Pregnancy. November 2016. http://www.marchofdimes.org/pregnancy/weight-gain-during-pregnancy.aspx