Should gestational weight gain recommendations be tailored by maternal characteristics?

Abstract

The authors tested whether the relation between gestational weight gain (GWG) and 5 adverse pregnancy outcomes (small-for-gestational-age (SGA) birth, large-for-gestational-age (LGA) birth, spontaneous preterm birth, indicated preterm birth, and unplanned cesarean delivery) differed according to maternal race/ethnicity, smoking, parity, age, and/or height. They also evaluated whether GWG guidelines should be modified for special populations by studying GWG and risk of at least 1 adverse outcome within different subgroups. Data came from a cohort of 23,362 normal-weight mothers who delivered singletons at Magee-Womens Hospital in Pittsburgh, Pennsylvania (2003-2008). Adequacy of GWG was defined as observed GWG divided by recommended GWG. The synergy analysis found that the combination of smoking, black race/ethnicity, primiparity, or short height with poor GWG was associated with an excess risk of SGA birth, while high GWG combined with each of these characteristics diminished risk of LGA birth in comparison with the same GWG among the women's counterparts. Nevertheless, there were no significant or meaningful differences in the risk of at least 1 adverse outcome between the GWG recommended by the Institute of Medicine in 2009 and the GWG that minimized risk of the composite outcome. These findings do not support the tailoring of GWG guidelines on the basis of a mother's smoking status, race/ethnicity, parity, age, or height among normal-weight women.

Figure 1.

Adjusted risk of adverse birth outcomes according to gestational weight gain (GWG) adequacy ratio, by smoking status, among deliveries occurring at Magee-Womens Hospital, Pittsburgh, Pennsylvania, 2003–2008. A) Nonsmokers (n = 20,268); B) smokers (n = 3,094). GWG adequacy ratio is defined as the ratio of observed GWG to expected (recommended) GWG at the gestational age at delivery. Recommended GWG is based on Institute of Medicine guidelines for normal-weight women (1). Solid line with filled circle, small-for-gestational age birth; dashed line with open circle, large-for-gestational age birth; solid line with filled triangle, spontaneous preterm birth; dashed line with open triangle, indicated preterm birth; solid line with filled square, unplanned cesarean delivery.

Figure 2.

Adjusted risk of adverse birth outcomes according to gestational weight gain (GWG) adequacy ratio, by maternal race/ethnicity, among deliveries occurring at Magee-Womens Hospital, Pittsburgh, Pennsylvania, 2003–2008. A) Non-Hispanic white (n = 19,655); B) non-Hispanic black (n = 3,707). GWG adequacy ratio is defined as the ratio of observed GWG to expected (recommended) GWG at the gestational age at delivery. Recommended GWG is based on Institute of Medicine guidelines for normal-weight women (1). Solid line with filled circle, small-for-gestational age birth; dashed line with open circle, large-for-gestational age birth; solid line with filled triangle, spontaneous preterm birth; dashed line with open triangle, indicated preterm birth; solid line with filled square, unplanned cesarean delivery.

Figure 3.

Adjusted risk of adverse birth outcomes according to gestational weight gain (GWG) adequacy ratio, by parity, among deliveries occurring at Magee-Womens Hospital, Pittsburgh, Pennsylvania, 2003–2008. A) Multiparous women (n = 12,405); B) primiparous women (n = 10,957). GWG adequacy ratio is defined as the ratio of observed GWG to expected (recommended) GWG at the gestational age at delivery. Recommended GWG is based on Institute of Medicine guidelines for normal-weight women (1). Solid line with filled circle, small-for-gestational age birth; dashed line with open circle, large-for-gestational age birth; solid line with filled triangle, spontaneous preterm birth; dashed line with open triangle, indicated preterm birth; solid line with filled square, unplanned cesarean delivery.

Figure 4.

Adjusted risk of adverse birth outcomes according to gestational weight gain (GWG) adequacy ratio, by maternal age, among deliveries occurring at Magee-Womens Hospital, Pittsburgh, Pennsylvania, 2003–2008. A) Maternal age ≥20 years (n = 21,607); B) maternal age 13–19 years (n = 1,755). GWG adequacy ratio is defined as the ratio of observed GWG to expected (recommended) GWG at the gestational age at delivery. Recommended GWG is based on Institute of Medicine guidelines for normal-weight women (1). Solid line with filled circle, small-for-gestational age birth; dashed line with open circle, large-for-gestational age birth; solid line with filled triangle, spontaneous preterm birth; dashed line with open triangle, indicated preterm birth; solid line with filled square, unplanned cesarean delivery.

Figure 5.

Adjusted risk of adverse birth outcomes according to gestational weight gain (GWG) adequacy ratio, by maternal height, among deliveries occurring at Magee-Womens Hospital, Pittsburgh, Pennsylvania, 2003–2008. A) Maternal height ≥157 cm (n = 20,949); B) maternal height <157 cm (n = 2,413). GWG adequacy ratio is defined as the ratio of observed GWG to expected (recommended) GWG at the gestational age at delivery. Recommended GWG is based on Institute of Medicine guidelines for normal-weight women (1). Solid line with filled circle, small-for-gestational age birth; dashed line with open circle, large-for-gestational age birth; solid line with filled triangle, spontaneous preterm birth; dashed line with open triangle, indicated preterm birth; solid line with filled square, unplanned cesarean delivery.

Figure 6.

Unadjusted association between gestational weight gain (GWG) adequacy ratio and risk of any adverse birth outcome, by maternal subgroup, among deliveries occurring at Magee-Womens Hospital, Pittsburgh, Pennsylvania, 2003–2008. “Any adverse birth outcome” was a composite measure comprising any 1 of following adverse birth outcomes: small-for-gestational-age birth, large-for-gestational-age birth, indicated preterm birth, spontaneous preterm birth, and unplanned cesarean delivery. A) Smokers (bolded lines) and nonsmokers; B) non-Hispanic black women (bolded lines) and non-Hispanic white women; C) primiparas (bolded lines) and multiparas; D) maternal age 13–19 years (bolded lines) and maternal age ≥20 years; E) maternal height <157 cm (bolded lines) and maternal height ≥157 cm. GWG adequacy ratio is defined as the ratio of observed GWG to expected (recommended) GWG at the gestational age at delivery. Recommended GWG is based on Institute of Medicine guidelines for normal-weight women (1). The solid lines represent the point estimate, and the dashed lines represent the 95% confidence bands.