This concern is valid for malnourished mothers, but it does not appear to be grounded for well-nourished mothers. Although we do not yet have a medical study that can speak directly to the question for well-nourished mothers, we have two reasons to be quite encouraged:
- A survey of 57 mothers who had breastfed during some or all of pregnancy recorded that the babies born to these mothers had healthy birth weights (birth weights averaged 7 lb 9 oz, and ranged from 5 lb 9 oz – 10 lbs 14 oz). (Moscone 1993)
- A recent review of the available research on breastfeeding and pregnancy as separate events revealed that as long as the mother is eating enough calories of a basic mixed diet, and as long as she is gaining weight within healthy parameters, there is ample reason to believe she can provide well for herself, her fetus and her nursling. (Adventures in Tandem Nursing, 2003)
Personally (and on the very nonscientific level), I nursed through my second pregnancy with no problems, and nursed both my son and daughter for 14 months. My son has always been very healthy and weighed 1.25 pounds more than my daughter did (whose pregnancy I did not nurse through) – he certainly didn’t seem to lack any nutrition. He also did not lose any weight after birth, as most babies do.
I know many other mothers who have nursed through pregnancy and often went on to tandem nurse. None of these moms/babies experienced any problems relating to infant weight gain or nutrition.