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Maternal age at childbirth tends to be increasing worldwide, as is insulin resistance or diabetes. The culprit: the tendency of birth weight to increase along with maternal age.

Mom's age at childbirth affects boy baby as adult

A mother's age at her child's birth may affect her male child's birth weight as well as his adult chance of becomming diabetic.

"Our findings indicate that women giving birth under 25 years, or over 34 years of age, might result in less favorable sugar handling and possibly higher risk for developing type 2 diabetes in their sons."

Charlotte Verroken MD, of the Department of Endocrinology of Ghent University Hospital in Ghent, Belgium.

Maternal age at childbirth tends to be increasing worldwide, but studies investigating the effects of this trend on the metabolic health of the baby are scarce. Whether or not and how this affects children is relatively unknown, but current thinking is that part of the association between maternal age and insulin resistance may be related to the tendency of birth weight to increase as maternal age rises.

The results were presented Friday, March 6, at ENDO 2015, the annual meeting of the Endocrine Society in San Diego.

"We found that in a group of healthy men between 25 and 45 years old, sugar handling was related to their mother's age at childbirth.

"Specifically, sons of mothers under 30 and over 34 years old at childbirth were more insulin resistant than were sons of mothers between 30 and 34 years old.

"Moreover, sons of mothers who were younger than 25 years old at childbirth had higher fasting blood sugar levels than sons of older mothers."

Charlotte Verroken MD

As part of a population-based sibling pair study in healthy men aged 25 to 45 years old, Verroken and her co-authors studied 689 healthy brothers between 25 and 45 years of age whose mean age was 33.9 years. The researchers had information on their birth weight, maternal and paternal age at childbirth, adult weight, height, body composition and blood pressure as well as on fasting cholesterol, glucose and insulin levels.

At childbirth, the mothers ranged in age from 15 to 48 years with an average age of 27 years. The mothers were divided into 4 groups according to maternal age at birth: under 25 years, 25 through 29 years, 30 through 34 years and 35 years and over.

The researchers determined the men's total cholesterol, glucose and insulin levels in fasting serum samples and they evaluated insulin resistance.

After adjusting for adult age and body mass index, research found that, as the mother's age increased the baby's birth weight increased, and his fasting glucose levels and insulin resistance values decreased.

The sons of mothers aged 30 to 34 at childbirth had significantly lower fasting insulin levels and insulin resistance values compared to sons of mothers in the other age groups, while sons of mothers aged under 25 years of age had higher fasting glucose levels compared to sons of mothers aged 30 through 34, and sons of mothers aged 35 and above.

These associations were independent of adult age, birth weight and body mass index. No associations were found between maternal age and body composition, blood pressure or cholesterol levels. The authors ask for further research before these conclusions can be generalized.

This study received no commercial funding.

Abstract
BACKGROUND: Although maternal age at childbirth tends to increase worldwide, studies investigating the effects of this trend on metabolic health in the offspring are scarce.
OBJECTIVE: We aimed to determine whether maternal age at childbirth is associated with adult body composition and parameters reflecting metabolic health in a cohort of young, healthy men.

METHODS: This study is part of a population-based sibling pair study in healthy men aged 25 to 45 years old. 689 subjects (mean age 33.9 +/- 5.4 years) for whom maternal data were available were included in the present analyses. Data collected in the study included birth weight, adult weight, height, DXA-derived body composition and blood pressure. Total cholesterol, glucose and insulin levels were determined in fasting serum samples. Insulin resistance was evaluated using the homeostasis model assessment of insulin resistance (HOMA-IR). Cross-sectional associations were investigated using linear mixed-effects modeling.

RESULTS: Maternal age at childbirth was 27.0+/-4.7 years (range 15-48) and was positively associated with birth weight (β=0.13; p=0.001). In their adult sons, maternal age at childbirth was inversely associated with fasting glucose levels (β=-0.12; p=0.001) and HOMA-IR values (β=-0.07; p=0.050) after adjustment for adult age and BMI. After further adjustment for birth weight, the associations between maternal age and glucose levels remained significant (β=-0.12; p=0.003), whereas the association between maternal age and HOMA-IR weakened (p = 0.092) and birth weight became an independent inverse predictor of HOMA-IR (β=-0.07; p=0.039). No associations were found between maternal age and body composition, blood pressure or cholesterol levels.

When subjects were divided into 4 groups according to maternal age at birth (<25, 25-29, 30-34 and ≥35 years), sons of mothers aged 30 to 34 at childbirth had significantly lower HOMA-IR values and fasting insulin levels compared to sons of mothers in the other age groups (p=0.007-0.015 for HOMA-IR, p=0.007-0.028 for insulin), whereas sons of mothers aged <25 had higher fasting glucose levels compared to sons of mothers aged 30-34 (p=0.010) and sons of mothers aged ≥35 (p=0.042). These associations were independent of adult age, BMI and birth weight.

CONCLUSION: Maternal age at childbirth is associated with birth weight and glucose metabolism in adulthood. Part of the association between maternal age and insulin resistance might be mediated through birth weight.

Founded in 1916, the Endocrine Society is the world's oldest, largest and most active organization devoted to research on hormones and the clinical practice of endocrinology. Today, the Endocrine Society's membership consists of over 18,000 scientists, physicians, educators, nurses and students in 122 countries. Society members represent all basic, applied and clinical interests in endocrinology. The Endocrine Society is based in Washington, DC. To learn more about the Society and the field of endocrinology, visit our site at http://www.endocrine.org. Follow us on Twitter at https://twitter.com/#!/EndoMedia.

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