Monday, August 09, 2010

Pregnant? Eating for 2? More like eating for 1.2.

When I practiced more traditional family medicine and saw my pregnant patients many rationalized rapid and extreme weight gains as a rite of pregnancy and not a worry because after all, they were "eating for two".

It's probably time to rethink those attitudes.

Last week a paper was published in the Lancet which looked at a within family comparison of pregnancy weight gain and baby birth weight.

The study was rather enormous in scope capturing 513,501 women and their 1,164,750 children. The findings were pretty straightforward too - babies of women who gained more than 50lbs during their pregnancies were roughly 1/3lb heavier at birth than those of women who gained between 17-22lbs.

Moreover, compared to those gaining 17-22 pounds, the bigger gaining mothers were 1.7 times more likely to have a high-birth-weight baby, and those gaining more than 53 pounds were 2.3 times more likely to do so.

Doesn't sound like much, but there are some other things to keep in mind when considering the results.

Excessive pregnancy related weight gain is a very real driver of sustained maternal obesity, and bigger babies have been shown to be at greater risk of becoming obese adults.

Why do bigger babies have a greater likelihood of turning out to be obese adults? The working theory in the paper is that the intra-uterine environments of babies born to women with greater pregnancy weight gains are different and that these differences in turn impact on dietary behaviours over the child's lifetime.

Of course it's also possible that the dietary habits in homes of women who gain excessive weight during pregnancy differ from those who don't with these differences nurturing (rather than naturing) an impact on dietary behaviours over the child's lifetime.

Either way one thing's for certain - pregnancy is a wonderful opportunity to explore your diet and remember that the "two" you're eating for, ain't exactly an equal in size.

Eating for 1.2 sounds about right.

David S. Ludwig, & Janet Currie (2010). The association between pregnancy weight gain and birthweight: a within-family comparison The Lancet : 10.1016/S0140- 6736(10)60751-9

Bookmark and Share


  1. mathematically speaking, if a 120 lb mother gives birth to a 6 lb baby, she would be eating for 1.05.

  2. John, you're forgetting about the other products of conception - placentas, increased intravascular volume etc.

  3. Anonymous10:36 pm

    I believe it takes about 300 extra calories a day after the first trimester to nurture a fetus. That's not a lot. However breast feeding on average burns 500 calories per day

  4. This is something that most mothers tend to ignore. You are right in pointing out that most mothers conveniently start eating for 2. You are also right to point out that losing pregnancy weight is extremely difficult. It is after the 2nd or 3rd pregnancy that women really give up with their weight. Thanks for the insights.

  5. Anonymous1:41 pm

    I gained an obscene amount of weight (50lbs!) and had a long, 7 lb baby. He was so scrawny, he needed preemie diapers.