April 26, 2018
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Maternal overweight associated with early puberty in girls

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Ai Kubo
Ai Kubo

The early onset of puberty in girls aged 6 to 11 years was associated with in utero exposure to maternal overweight and hyperglycemia, according to findings published in the American Journal of Epidemiology.

Adverse health consequences, such as obesity, type 2 diabetes, polycystic ovary syndrome and cancer, have been linked to early onset of puberty. Specifically, for girls, early puberty onset can increase the risk for depression and anxiety and has been associated with earlier sexual initiation and pregnancy, according to the study background.

“Little is known regarding the associations between maternal factors and pubertal timing, generally. The recent study adds to the current knowledge because of the size and diversity of the population,” Ai Kubo, MPH, PhD, research scientist with Kaiser Permanente Northern California, told Endocrine Today.

Kubo and colleagues utilized electronic patient records from Kaiser Permanente to create a cohort of 15,267 mother-daughter pairs. Among the girls, 5,625 were non-Hispanic white, 3,175 were Asian, 3,844 were Hispanic, 988 were black and 1,635 were other ethnicities. Girls born between 2003 and 2006 who had continuous insurance coverage and Kaiser Permanente membership and no conditions that affect pubertal development were assessed for Tanner staging by pediatricians until March 2017; breast Tanner stage data were available for 14,760 pairs and pubic hair Tanner stage data for 14,063 pairs.

Kubo and colleagues calculated maternal BMI during pregnancy. Women classified as underweight had BMI less than 18.5 kg/m2 (n = 165), and women with BMI between 18.5 kg/m2 and 24.9 kg/m2 were considered normal weight (n = 6,468). Women were considered to have overweight if BMI was between 25 kg/m2 and 29.9 kg/m2 (n = 4,835) and obesity if BMI was at least 30 kg/m2 (n = 3,799). Maternal glucose level data were identified from Kaiser Permanente’s gestational diabetes mellitus registry: blood glucose concentrations less than 140 mg/dL (n = 11,364) or at least 140 mg/dL (without gestational diabetes, n = 1,846; with gestational diabetes, n = 977).

Earlier breast onset was 30% more likely for daughters of mothers with obesity than those whose mothers were classified as normal weight (HR = 1.39; 95% CI, 1.3-1.49). Conversely, girls whose mothers were underweight during pregnancy were less likely to experience early breast onset (HR = 0.75; 95% CI, 0.58-0.97). An approximate 7-month difference was observed in the timing of breast onset between girls whose mothers had obesity vs. daughters of underweight mothers, according to the study.

Maternal obesity was significantly associated with earlier pubic hair onset. When maternal BMI and children’s pubic hair onset were stratified by ethnicity, no significant association was found among black girls, but Asian girls (and those in the “other” category) whose mothers had obesity experienced a 50% higher risk of earlier pubic hair onset vs. Asian girls whose mothers were of normal weight (HR = 1.53; 95% CI, 1.24-1.9). Among non-Hispanic white and Asian girls, maternal overweight was significantly associated with pubarche, but the relationship was not observed among Hispanic girls. Researchers identified a significant inverse association between maternal overweight and pubarche among black girls (HR = 0.7; 95% CI, 0.48-1).

No associations were observed between maternal hyperglycemia in gestational diabetes and breast onset or between pubic hair onset and maternal hyperglycemia regardless of gestational diabetes status. However, researchers found maternal hyperglycemia without gestational diabetes and earlier breast onset were significantly associated (HR = 1.12; 95% CI, 1.03-1.21).

Kubo said discovering the significant association between breast development and maternal hyperglycemia without gestational diabetes was surprising.

“It might be because of the intensive care that women with a [gestational diabetes] diagnosis receive at Kaiser Permanente; this may have resulted in lower gestational weight gain and better lifestyle (diet/exercise), leading to better pregnancy outcomes as well as child development,” she told Endocrine Today.

The study results indicate that maternal metabolic factors during pregnancy are important to the timing of puberty in girls, Kubo said.

“Our findings underscore the importance of women who are trying to be pregnant or are pregnant paying attention to their lifestyle and weight, and doing their best to maintain healthy weight, diet and exercise habits,” she said. “For women who are overweight or have hyperglycemia, it might be good to practice a healthy lifestyle after birth of their baby, including breast-feeding (which also has been shown to be related to later pubertal onset), healthy diet, encouraging the child to exercise (high exercise is related to later puberty), minimizing exposure to endocrine disruptors, such as BPA or other environmental toxins, and getting enough sleep.” – by Marley Ghizzone

Disclosures: Kubo reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.