Maternal weight gain is associated with "some outcomes"
From the AHRQ Women’s Health Highlights page:
Maternal weight gain is associated with some outcomes for mothers and babies.
According to this review of the scientific evidence, there is a strong association between a pregnant woman’s weight gain and the following outcomes: preterm birth, total birthweight, low birthweight, large-and small-for-gestational-age infants, and very large infants. The researchers found a moderate association between maternal weight gain and two additional outcomes: cesarean delivery and postpartum weight retention for up to 3 years following childbirth. Outcomes of Maternal Weight Gain, Evidence Report/Technology Assessment No. 168 (AHRQ Publication No. 08-E009) (AHRQ Contract 290-02-0016).
The 1,038 page report is available online at http://www.ahrq.gov/clinic/tp/admattp.htm.
The review’s executive summary details its shortcomings.
Existing research is inadequate to permit objective assessments of the range of harms and benefits of providing all women, irrespective of age, race or ethnicity, or pregravid BMI, with the same recommendation for weight gain in pregnancy.
Clear clinical recommendations based on this systematic review will be challenging to formulate because of major shortcomings in the body of research investigating gestational weight gain and pregnancy outcomes. The research is almost all observational; it lacks uniformity of definitions, methodologies, and analyses. To understand fully the impact of gestational weight gain on the short- and long-term outcomes for women and their offspring will require that researchers use consistent definitions of gestational weight gain and the outcomes, describe the criteria used to assess confounding in their analysis, use statistical methods that allow for the evaluation of more than one outcome at a time, make improvements in study design to allow better collection of weight and weight gain data, and follow women and infants for longer periods.