#22 Does 9 months of "eating for two" give you a bigger baby or a bigger bum?

FACT OF THE DAY: Women in some cultures near starve themselves during pregnancy in hope of giving birth to a smaller baby that is safer to deliver

What’s one of the first thing people say to you once you’re pregnant? After the initial congratulations, often the next reaction along with your celebratory cup of tea is encouragement to eat more, saying “Go on, have another biscuit, now that you’re eating for two”.

Our culture’s obsession with feeding up pregnant women probably relates back to the days when food was scarce. But food is not so scarce these days, in fact for most of us it’s more than plentiful!

The current NHS advice specifically says “you don’t have to eat for two” during pregnancy. Making sure you eat sufficient vitamins and minerals while pregnant is now recognised as more important than extra food.

Exact figures vary, but it seems that for the first six months of pregnancy you don’t need any extra calories as your body becomes more efficient, and for the final three months just an extra 200-300 calories per day are needed (equivalent to a couple of slices of toast, or one Mars Bar).

That’s really very little excuse to be putting our hands in the cookie jar too often. It also explains why even in famine conditions women are able to produce babies.

If this very modest extra calorie requirement were more widely known, would it change our eating habits during pregnancy?

Cultural attitudes are hard to shift, and “eating for two” is a phrase that (despite its inaccuracy) is part of our psyche – it trips of the tongue unthinkingly by anyone and everyone. Until someone comes up with a nifty equivalent phrase that sums up “no extra food needed during pregnancy until the last three months and even then you don’t even need that much” I think it will be around for a long while yet.

I was interested to know; Does the amount you eat during pregnancy affect the size of your baby?

The general consensus seems to be that unless a woman is severely under or over eating, how much she eats during pregnancy does not really affect the baby’s birth weight. The average weight gain in the UK is 11kg, but putting on more weight doesn’t mean the baby will be larger at birth, and putting on less weight won’t create a smaller baby (unless the gain is less than 7kg, although it does depend whether the mother was over or underweight to start with).

What is this weight gain made up of? (These are approximate figures)

<><><><> </><><><><> </><><><><> </><><><><> </> <><><><> </> <><><><> </><><><><> </><><><><> </> <><><><> </> <><><><> </><><><><> </><><><><> </> <><><><> </> <><><><> </><><><><> </><><><><> </> <><><><> </> <><><><> </><><><><> </><><><><> </> <><><><> </> <><><><> </><><><><> </><><><><> </> <><><><> </> <><><><> </><><><><> </><><><><> </> <><><><> </> <><><><> </><><><><> </><><><><> </> <><><><> </>

Baby	3-4 kg
Placenta	1 kg
Amniotic fluid	1 kg
Increased maternal blood volume	2 kg
Increased maternal fluid in tissues	1.5 kg
Uterine enlargement	1 kg
Breast enlargement	0.5 kg
Total	10-11kg

However, in some developing countries where women start off their pregnancy severely undernourished, their diet during pregnancy can affect the birth weight of their baby. I have read about some women who put on as little as 3kg during pregnancy. Their babies will have a seriously low birth weight. Low birth weight in this scenario is associated with many health problems, and is a common cause of early infant death in the non-Western world.

However without realising the problems of low birth weight in their babies, women in some cultures are so concerned with surviving the ordeal of childbirth that they actually eat very little on purpose.

This is called ‘eating down’. The women hope that by eating less they will have a smaller baby that will be easier to deliver. This has been observed around the world.

Among the cattle-herding Masai of southern Kenya “during the last 3 or 4 months of pregnancy the women abandons her normal diet and exists on a near starvation diet, consisting primarily of broth of lungs, liver, and kidneys, cooked with a bitter bark. The last month, she drinks only milk”. While these are common foods for Masai they would normally be eating plentiful porridge, grain and beans as well.

In Bangladesh pregnant women are encouraged not to eat too much so that their baby will be small and more likely to be born without difficulty.

Other cultures across the world (the Enga of Papua New Guinea, the rural Malays, the Ainu of Japan and the Maya from Guatemala) try to achieve the same objective through encouraging pregnant women to work hard and do lots of heavy physical exercise in the last few months of pregnancy, rather than by eating less. Similarly in Nepal women are aware that smoking stunts a baby’s growth, so some women intentionally continue to smoke during pregnancy in the hope of producing a smaller baby. 

The long term impact of ‘eating down’ is unclear, but there is some evidence to show that the baby’s birth weight may only be slightly affected, but the mother suffers as the baby’s nutritional demands are met from her meagre stores.

(For balance I should also say that in many other non-Western cultures women are given extra food during pregnancy and their food cravings are satisfied.)

So the answer to my initial question seems to be, it all depends where you're starting from. For the majority of us who are not undernourished to start off with, yes, eating for two will give us a bigger bum at the end of the pregnancy!

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If you would like to read more, take a look at;

Devries, M ‘Cry babies, culture and catastrophe: Infant temperament among the Masai’ in ed Scheper-Hughes, N (1987) Anthropological approaches to the treatment and maltreatment of children Dordrecht : Reidel

Enga Birth, Maturation and Survival: Physiological Characteristics of the Life Cycle in the New Guinea Highlands in Ed MacCormack, Carol P (1982) Ethnography of Fertility and Birth Academic Press : New York

Editors Richardson, SA and Guttmacher, A (1967) Childbearing – its social and psychological aspects The Williams and Wilkins Company

Sarah Blaffer Hrdy (1999) Mother Nature; A History of Mothers, Infants and Natural Selection  United States of America : Pantheon Books