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Nutrition and weight changes during pregnancy and breastfeeding

Nutrition and weight changes during pregnancy and breastfeeding

During pregnancy and breastfeeding it is crucial for mothers to have access to a wide range of nutrients in order to meet the physiological demands of their growing child.

In the first 6 months from birth, babies will more then double their birth weight just from exclusive breastfeeding. This increased nutritional demand should be met by mother’s consuming a well-balanced and nutritious diet from pre-conception until the end of the breastfeeding journey.

Women who are vegetarian/vegan need to ensure a diet containing foods rich in vitamins B12, B2 vitamin A and vitamin D. Also important are nutrients such as iron, folate, zinc, calcium and energy dense proteins (such as tofu, bean and soy products).

Do I need to drink more water?

It is often suggested you must increase your fluid intake when pregnant or breastfeeding, however this is not based on conclusive evidence. Instead, you should drink to thirst and monitor for signs of dehydration should this be necessary (dark urine, dry mouth).

Pregnancy weight changes

Throughout pregnancy, it is expected that women’s weight will increase. Depending on pre-pregnancy BMI, the expected (or optimal) weight gain range varies.

The national standards for recommended weight gain in pregnancy are:

Pre-pregnancy weight                                   Recommended weight gain

Underweight (BMI below 18.5)                  13-18 kg

Healthy weight (BMI 18.5 to 24.9)             11-16 kg

Overweight (BMI 25 to 29.9)                        7-11 kg

Obese (BMI 30 or more)                               5-9 kg

Evidence demonstrates the risks of obesity increase with subsequent pregnancies in high income earning countries where food is abundant and previous ‘baby weight’ is not lost prior to pregnancy. Women who have not returned to pre-pregnancy weight by six months postpartum are also at an increased risk of developing long-term obesity.

However, it is not uncommon for women to lose 500-1000gms/month after the first 4 weeks following delivery. This is most common in women who are exclusively breastfeeding due to the energy requirements of lactation.

It has been found that women generally lose between 80-85% of their pregnancy weight gain during their baby’s first 6 months. 

Breastfeeding and its impacts

While exclusively breastfeeding, there are additional energy requirements of 500+ calories per day.*

*This is based on the average quantity of breastmilk produced every 24hrs for exclusively breastfeeding mothers (780mls).

780ml/day x (67 kcal/100ml)/ 0.8 = 653 kcal/day

This means the energy efficiency of milk production is 80%.

Well nourished mothers already consuming a balanced diet should aim to meet this additional requirement by consuming an additional 500kcal per day in the form of nutritious snacks.

Exercise and diet to lose weight during breastfeeding

Mothers aiming to lose weight while breastfeeding may choose exercise and moderate calorie restriction (up to 500kcal below estimated needs). Studies suggest weight loss up to 2kg per month does not negatively affect lactation (for women in the obese BMI category pre-pregnancy). 

Additionally, aerobic exercises such as running, cycling, swimming, dance and other cardiovascular exercises have no adverse effects on lactation. (Based on studies of women exercising 45 mins/day x5 days per week)

As with all cases, it is best to consult with your healthcare provider to determine what diet, nutritional balance and exercise amount is right for you specifically.

Written by Keryn Thompson RM & IBCLC (L-301766) 


Bever Babendure, J., Reifsnider, E., Mendias, E., Moramarco, M. and Davila, Y., 2015. Reduced breastfeeding rates among obese mothers: a review of contributing factors, clinical considerations and future directions. International Breastfeeding Journal, 10(1).

De Jersey, S., Nicholson, J., Callaway, L. and Daniels, L., 2012. A prospective study of pregnancy weight gain in Australian women. Australian and New Zealand Journal of Obstetrics and Gynaecology, 52(6), pp.545-551.

Gilmore, L., Klempel-Donchenko, M. and Redman, L., 2015. Pregnancy as a window to future health: Excessive gestational weight gain and obesity.

Herring, S., Nelson, D., Davey, A., Klotz, A., Dibble, L., Oken, E. and Foster, G., 2012. Determinants of Excessive Gestational Weight Gain in Urban, Low-Income Women. Women's Health Issues, 22(5), pp.e439-e446.

Lambrinou, C., Karaglani, E. and Manios, Y., 2019. Breastfeeding and postpartum weight loss. Current Opinion in Clinical Nutrition & Metabolic Care, 22(6), pp.413-417.

Li, N., Liu, E., Guo, J., Pan, L., Li, B., Wang, P., Liu, J., Wang, Y., Liu, G., Baccarelli, A., Hou, L. and Hu, G., 2013. Maternal Prepregnancy Body Mass Index and Gestational Weight Gain on Pregnancy Outcomes. PLoS ONE, 8(12), p.e82310.

Mate, A., Reyes-Goya, C., Santana-Garrido, Á. and Vázquez, C., 2021. Lifestyle, Maternal Nutrition and Healthy Pregnancy. Current Vascular Pharmacology, 19(2), pp.132-140.

Muktabhant, B., Lawrie, T., Lumbiganon, P. and Laopaiboon, M., 2015. Diet or exercise, or both, for preventing excessive weight gain in pregnancy. Cochrane Database of Systematic Reviews, 2015(6).

Nascimento, S., Surita, F. and Cecatti, J., 2012. Physical exercise during pregnancy. Current Opinion in Obstetrics & Gynecology, 24(6), pp.387-394.

Ruchat, S., Davenport, M., Giroux, I., Hillier, M., Batada, A., Sopper, M., Hammond, J. and Mottona, M., 2012. Nutrition and Exercise Reduce Excessive Weight Gain in Normal-Weight Pregnant Women. Medicine & Science in Sports & Exercise, 44(8), pp.1419-1426.

Shub, A., Huning, E., Campbell, K. and McCarthy, E., 2013. Pregnant women’s knowledge of weight, weight gain, complications of obesity and weight management strategies in pregnancy. BMC Research Notes, 6(1).

Stengel, M., Kraschnewski, J., Hwang, S., Kjerulff, K. and Chuang, C., 2012. “What My Doctor Didn't Tell Me”: Examining Health Care Provider Advice to Overweight and Obese Pregnant Women on Gestational Weight Gain and Physical Activity. Women's Health Issues, 22(6), pp.e535-e540.

Thangaratinam, S., Rogozinska, E., Jolly, K., Glinkowski, S., Roseboom, T., Tomlinson, J., Kunz, R., Mol, B., Coomarasamy, A. and Khan, K., 2012. Effects of interventions in pregnancy on maternal weight and obstetric outcomes: meta-analysis of randomised evidence. BMJ, 344(may16 4), pp.e2088-e2088.



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