Your pregnancy weekly weight gain

If you think your pregnancy is an excuse to eat like a horse think again, because it could put both you and your baby at risk. There’s a lot of research pointing to the risks that come with being overweight or obese during pregnancy and recent research also suggests that babies born to obese moms have a higher risk of asthma.

How your weight affects your pregnancy and birth

Gaining the right amount of weight during pregnancy is critical to giving your baby a healthy start in life – but almost half of pregnant women (including those who are already overweight) gain more weight than they should during pregnancy. This can compromise your unborn baby’s health because fat cells are active, producing chemicals that cause inflammation in the body that can affect your baby’s immune system and his lungs. Plus, putting on too much weight can make it more difficult for your caregivers to monitor your baby’s health and wellbeing, as well as putting you at higher risk of developing high blood pressure (which in turn raises the risk of pre-eclampsia) and gestational diabetes, and miscarriage.

You’re also more likely to have labor complications that mean you need a caesarean delivery. These all put your baby’s health and wellbeing at risk. Babies born to overweight and obese mums also are at increased risk of preterm birth. This is the leading cause of newborn death, and babies who survive preterm birth often face lifetime health challenges. Even babies born just a few weeks too soon have higher rates of death and disability than full-term babies, and often need long periods of special care in a neonatal intensive care unit (NICU). They also are more susceptible to certain birth defects, especially neural tube defects such as spina bifida.

Studies also show that if you’re an overweight or obese mum-to-be this can affect your baby’s weight as he grows – children born to women who match or exceed the guidelines for pregnancy weight gain are four times as likely to be overweight in childhood and are more likely to develop high blood pressure.

How much weight should you gain?

Experts recommend that obese women – those with a body mass index of 30 or more – limit their weight gain to 11 to 20 pounds over nine months. Overweight women (BMI 25 to 29.9) are advised to gain 15 to 25 pounds over nine months, while underweight women (BMI less than 18.5) should gain 28 to 40 pounds, and normal-weight women (BMI 18.6 to 24.9) should gain 25 to 35 pounds.

Weekly pregnancy weight gain

You will only be weighed on your first antenatal check, or booking in check with the midwife. After this you will only be weighed if the midwives think it necessary. Typically, you can expect to gain one pound per month during your first trimester (weeks 0-12), half a pound per week during your second (weeks 13-28) and about a pound a week during your third trimester (weeks 29-40). During the last couple of weeks this may increase as your appetite keeps pace with your baby laying down fat to insulate him after he’s born.

These figures are averages: your individual weight gain will depend on your pre-pregnancy weight, and your pattern of eating – for example, you may feel ravenous during your first trimester and gain more weight then, or gain little or no weight early on because morning sickness puts you off eating. You may then feel hungry again during your second trimester and put on more weight then, but during your third trimester you may eat less if you are suffering from heartburn caused by your growing baby pressing up against your stomach. It also depends on how many babies you are carrying – women expecting twins or more can gain up to 45 to 50 pounds depending on how much they weighed when they became pregnant.

Staying on track with weight gain

Your best bet for avoiding excess weight gain in pregnancy is to stick to a healthful diet that incorporates plenty of fresh fruits and vegetables, whole grains, lean meat, poultry and fish, and healthy fats. Avoid eating for two – you don’t need to consume any additional calories during your first trimester and only need about 300 additional calories per day (for example, a yogurt teamed with a banana or a slice of toast) in the second and third trimesters. The thing to remember is that after your baby is born you will probably be keen to lose any weight put on and with a young baby in tow this can be difficult. Trying (sensibly) to put as little weight on as possible during pregnancy will help you once your baby is born and you are keen to return to your old self!

Watch our video on Safe exercising post-natally and safe exercising for mums-to-be for ideas on gentle exercises recommended at this stage.

The information in this feature is intended for educational purposes only. If you have any concerns about your health, the health of your child or the health of someone you know, please consult with a doctor or other healthcare professional.

Last Modified: 19/08/2009