UPDATED: Dieting and weight-gain during pregnancy

Obesity is a significant problem in New Zealand, with latest figures showing one adult in three is overweight and a further one in four is obese*.

A research paper due to be published on Wednesday (NZT) in the Journal of the American Dietetic Association looks at determinants of excessive weight gain during pregnancy. It appears that women who diet habitually prior to becoming pregnant gain more weight during pregnancy. Repeated cycles of dieting and over-eating may distort one’s ability to perceive hunger and satiety.

It is important to avoid excess weight gain during pregnancy to reduce the risk of gestational diabetes, cesarean sections and large babies. It was recommended by the authors that counseling and extra support could be helpful during pregnancy to encourage healthy eating, increased activity levels and ways to eliminate the stress that can lead to over-consumption of food.

For a copy of the research, please contact the Science Media Centre.

Carol Perwick, a dietitian at Christchurch Women’s Hospital comments:

“In pregnancy women need to be aware that there is a need for an increase in vitamins, minerals and other nutrients but there is only a small increase in energy required.

“In order to consume more nutrients in your diet without increasing your energy intake at the same time it is important that women increase their fruit and vegetable intake to include at least 5+ servings/day and choose foods that are less processed.

“This translates to choosing food:

1. with less taken out of them e.g. wholegrain breads rather than white breads, fruit rather than fruit juice.

2. with less added to them, especially fats and sugars e.g. cake, chips, sweetened breakfast cereals.

“Use pregnancy as a time to motivate you to more consistently choose the healthier option. Changing food preference now benefits you, your baby and your immediate family both now and in the future. Exercise is frequently reduced but if health permits, pregnant women need to maintain regular activity at a level they are accustomed to.

“Check with your healthcare provider whether restrictions may apply. For most women though a daily walk should be encouraged to maintain fitness and a sense of well being.”

Helen Little, dietitianalso  at Christchurch Women’s Hospital comments:

“I agree that in NZ we also have an increasing prevalence of obesity amoung women of child bearing age and that preconception care or screening in early pregnancy for women who need dieitary advice regarding  is required.

“We have very little evidence of the proportion of women who are gaining in excess of recommendations during pregnancy as for some time now there has been a move away from regular weighing of women by their lead maternity carers in NZ.

“We have a requirement on booking to birth at Christchurch Women’s Hospital the pre-pregnancy weight, height and BMI are to be on the referral document. Often we get the height and weight but not BMI. This is partly to keep a track on the increasing prevalence of obesity but also it is a requirement that women with a BMI over 30 cannot birth at primary units.

“We would have very few women who are weighed prior to delivery in birthing suite and I would say not many women are weighed at their subsequent antenatal visit unless attending our Diabetes in Pregnancy clinic.

“I have not seen the formula they used before to apply the adequacy ratio of weight gain. We would use BMI specific recommendations for women we see in pregnancy who are overweight and agree their are no formal recommendations for obese pregnant women.

“Dietary restrictions need to ensure the nutrient intake is still adequate for minerals, vitamins and micronutrients not just calories.”

Christine Cook, a community liaison dietitian from Auckland, comments:

“This new research suggests that people who regularly diet may be prone to gaining more weight when they become pregnant. It’s important to emphasise that pregnancy is not the right time to try to lose weight; the focus should be on having a nutrient-dense diet to provide all the extra vitamins and minerals that are needed by the body. However, if you were overweight at the beginning of your pregnancy, you will need to control the amount that you eat in order to limit your weight gain.

My advice to pregnant women is to concentrate on the quality of what you eat.  You are literally feeding two in terms of accessing enough vitamins and minerals (micro nutrients) to enable and support all the body processes.  This brings you to the number one healthy eating rule – eat many kinds of food! It is easy to obtain all the nutrients you need by selecting food from all four food groups; these are:

– Vegetables and fruit – go for a colourful plate and eat heaps.

– Bread & cereals – wholegrain are best as they are much richer in fibre, vitamins and minerals; be careful of this particularly if you limit gluten.

– Milk and milk products – go for a low fat variety as this is also higher in calcium and so better for your and your baby’s bones.

– Meat/fish/chicken/legumes – have fish (fresh or canned) once or twice/week if possible but also lean red meat for iron.

-Keep your choices within these groups varied.  Most women will find that they need to be careful of food that is high in fat and or sugar (for example pies, cakes, croissants, crisps, chips) as well as sugary drinks. These contribute lots of energy (calories) but a limited range of micro-nutrients.

Further information

New Zealand Dietetic Association

fact sheet on Nutrition for a healthy pregnancy.

Reference: Mumford SL, Siega-Riz AM, Herring A, Evenson KR. Dietary restraint and gestational weight gain. J Am Diet Assoc, 2008; 108: 1646-1653.

*Ministry of Health. 2008. A Portrait of Health. Key Results of the 2006/7 New Zealand Health Survey. Wellington: Ministry of Health.

To speak to this expert or others, contact the Science Media Centre on 04 499 5476 or smc@sciencemediacentre.co.nz

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