Why your weight matters before and during pregnancy
Gaining weight is a normal, healthy part of pregnancy. After all, you are growing a whole new human in your belly!
However, it’s not always easy to know how much weight gain is healthy during pregnancy. Gaining too much or not enough weight can put you and your baby at risk of complications, which is why we’ve teamed up with the Monash Centre for Health Research and Implementation to develop an easy-to-use calculator to check your weight is healthy, from conception through to childbirth.
Being a healthy weight before you start trying to conceive is the healthiest way to start a pregnancy for you and your baby. Not only is it important for fertility, it sets you up for healthy weight gain throughout your pregnancy. It also indicates you’ve formed healthy habits that will serve you well throughout this life stage.
During the first twelve weeks of pregnancy, the guidelines recommend women gain 0.5 – 2kgs, depending on their conception weight1. However, a significant number of women exceed recommendations early in pregnancy, with one study showing 10% of women gain more than the total recommended weight before their first hospital visit2. Others may struggle to gain weight at all.
With morning sickness and other pregnancy symptoms, the first trimester can be challenging. The good news is, these symptoms tend to ease during the second trimester. Try your best to eat fresh, healthy foods, get some exercise in and regularly monitor your weight. If you’re really struggling, aim to refocus on healthy habits when you’re feeling better in the second trimester.
During the second and third trimester, you should gain weight at a steady rate. Depending on your pre-pregnancy weight, the recommended weekly weight gain is between 200-500grams per week. Keep in mind, it’s normal for weight gain to fluctuate from time-to-time. If you’re concerned, speak to your doctor.
At least 40% of Australian pregnant women exceed the healthy weight gain recommendations for pregnancy3. Being an unhealthy weight before you fall pregnant and gaining too much weight during pregnancy puts you at higher risk of a number of complications4, including:
- High blood pressure, also known as hypertension, during pregnancy
- Gestational diabetes
- Having a caesarean birth
- Having a large-for-gestational-age baby.
You’re also less likely to return to the weight you were before you were pregnant5, putting you at risk of being an unhealthy weight for future pregnancies.
For some women, severe morning sickness or a loss of appetite can make it difficult to gain enough weight during pregnancy. Not gaining enough weight can increase the risk of:
- Having a small-for-gestational-age baby6
- Your baby being born before 37 weeks gestation7
The Healthy weight gain during pregnancy calculator is based on the Institute of Medicine Weight Gain Recommendation for Pregnancy 20099. It is not accurate for multiple pregnancies.
Calculator and content reviewed by Dr Cheryce Harrison and Prof Helena Teede, Monash Centre for Health Research and Implementation, Monash University
Published May 2018
1 Weight gain during pregnancy. Committee Opinion No. 548. American College of Obstetricians and Gynecologists. Obstet Gynecol 2013;121:210–2.
2 Jersey et al., A prospective study of gestational weight gain in Australian women, Australian New Zealand Journal of Obstetrics and Gynaecology, November 2012
3 deJersey et al., A prospective study of gestational weight gain in Australian women, Australian New Zealand Journal of Obstetrics and Gynaecology, November 2012
4 Royal Australian College of Obstetricians and Gynaecologists, Management of Obesity in Pregnancy – College Statement C-Obs 49, March 2013
5 Mannan et al., Association between weight gain during pregnancy and postpartum weight retention and obesity: a bias-adjusted meta-analysis, Nutrition Reviews, June 2013
6 Ruwanpathirana, T. & Fernando, D.N., Risk factors for small for gestational age babies, Indian J Pediatr, October 2014.
7 Lengyal et al., Effects of Modifiable Risk Factors on Pre-term Birth: A Population based cohort study, Maternal and Child Health Journal, April 2017
9 Rasmussen, K., & Yaktine AL (Eds). Institute of Medicine and National Research Council Committee to Reexamine IOM Pregnancy Weight Guidelines, Weight Gain During Pregnancy: Reexamining the Guidelines2009, Washington DC: National Academic Press.