Lifestyle Counseling May Improve Some Pregnancy Outcomes

Laurie Barclay, MD

May 17, 2011

May 17, 2011 — Lifestyle counseling of high-risk pregnant women controls newborn birth weight but fails to affect maternal gestational diabetes mellitus (GDM), according to the results of a cluster-randomized trial reported online May 17 in PLoS Medicine.

"High intake of saturated fat, low intake of polyunsaturated fat, and excessive gestational weight gain may increase the risk of GDM," write Riitta Luoto, from UKK Institute for Health Promotion Research in Tampere, Finland, and colleagues. "Physical activity is also associated with decreased risk of GDM. Lifestyle modifications have been shown to be a valuable adjunctive therapy of GDM but to date there are no adequately powered trials on primary prevention of GDM."

The goal of the NELLI study was to assess the effect of lifestyle counseling in pregnant women at high risk for GDM on development of maternal GDM and on reducing high birth weight in the newborns. In 14 municipalities in Finland, 2271 women were screened with an oral glucose tolerance test (OGTT) at 8 to 12 weeks of gestation. This identified 399 euglycemic women with 1 or more risk factors for GDM, namely body mass index (BMI) of 25 kg/m2 or more, glucose intolerance or newborn macrosomia (≥ 4500 g) in a previous pregnancy, family history of diabetes, and age 40 years or older.

Women in the intervention group received individual intensified counseling regarding physical activity, diet, and weight gain at 5 antenatal visits. The main maternal study endpoint was incidence of GDM identified by OGTT, and the main neonatal study endpoint was newborn birth weight adjusted for gestational age. Maternal weight gain and insulin requirement during pregnancy were also assessed. Cluster, maternity clinic, and nurse level effects, as well as age, education, parity, and prepregnancy BMI, were adjusted for in multilevel analyses.

Changes in physical activity and in dietary composition reflected good adherence to the intervention. GDM, defined as at least 1 abnormal value in 2-hour OGTT at 26 to 28 weeks of gestation, developed in 15.8% (34/216) of women in the intervention group vs 12.4% (22/179) of those in the usual-care group (absolute effect size, 1.36; 95% confidence interval [CI], 0.71 - 2.62; P = .36).

Compared with the usual-care group, the intervention group overall had lower neonatal birth weights (absolute effect size, −133 g; 95% CI, −231 to −35; P = .008) and a lower proportion of large-for-gestational-age (LGA) newborns (26/216, 12.1% vs 34/179, 19.7%; P = .042).

For adherent women in the intervention group vs those in the usual-care group, the risk for GDM, defined as at least 1 abnormal value in 2-hour OGTT at 26 to 28 weeks of gestation, newborn birth weight of at least 4000 g, or use of insulin or other diabetic medication, was 27.3% vs 33.0% (P = .43), and the risk for LGA newborns was 7.3% vs 19.5% (P = .03).

"The intervention was effective in controlling birthweight of the newborns, but failed to have an effect on maternal GDM," the study authors write.

Limitations of this study include lack of late pregnancy measurement of maternal glucose intolerance and lack of blinding.

"Results from ongoing clinical trials may strengthen the evidence on the effectiveness of lifestyle modifications on maternal and fetal hyperglycemia and its consequences," the study authors conclude. "The findings of our study emphasize counseling on the topics of physical activity, diet, and weight gain in maternity care especially for women at risk for GDM in order to prevent LGA newborns possibly causing problems in delivery, and both the mother's and the child's later weight development."

(Finnish) Diabetes research fund, and Competitive research funding from Pirkanmaa hospital district, Academy of Finland, Ministry of Education, and Ministry of Social Affairs and Health supported this study. The study authors have disclosed no relevant financial relationships.

PLoS Med. Published online May 17, 2011.

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