— Higher risks of hypertension, insulin resistance
Women who gained both excessive and insufficient weight during pregnancy had children who were at increased risk for adverse cardiometabolic risk factors, researchers in Hong Kong found.
There was a U-shaped relationship between maternal gestational weight gain and increased risks of childhood insulin resistance and hypertension when mothers gained either more or less weight than recommended by the 2009 Institute of Medicine (IOM) gestational weight guidelines, reported Ronald C. W. Ma, MD, of The Chinese University of Hong Kong, and colleagues.
Moreover, compared to children whose mothers gained a normal amount of weight during pregnancy, there was a positive association between gestational weight gain and body size and adiposity in these children, the authors wrote in Diabetologia
"Most earlier studies have focused on a limited number of offspring characteristics, such as childhood obesity or blood pressure," Ma told MedPage Today in an email. "The new insights gained from our study mainly relate to the multiple metabolic abnormalities present in children born to mothers who gained excessive weight or inadequate weight."
The authors stated that previous studies have linked prenatal under-nutrition with the risk of cardiovascular and metabolic disease later in life and found a generally positive association between maternal gestational weight gain and obesity in offspring.
But Ma added in an email that this study examined both linear and non-linear associations between gestational weight and cardiometabolic risk factors in children in order to determine a U-shaped association, which highlights the existence of "optimal ranges" for physiological processes such as gestational weight gain.
Researchers examined a sample of 905 mother-child pairs from the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study in Hong Kong, who returned for a follow-up assessment from 2009 to 2013 when offspring were age 7. Eligible participants had term pregnancies (≥37 weeks) and complete data on gestational weight gain. Women of non-Chinese ancestry and "glucose measurements beyond the setting of the HAPO study" were excluded, the authors said.
They distributed questionnaires to study participants and performed clinical examinations to determine skinfold thickness. Researchers also administered Oral Glucose Tolerance Tests (OGTT) to measure plasma glucose, insulin levels and sensitivity, and beta cell functioning, the authors said.
Overall, women had an average pre-pregnancy BMI of 20.9 and a mean weight change of 15.2 kg from pre-pregnancy to delivery. A similar percentage of women gained weight within IOM weight recommendations (41.8%) and above them (41.0%), with just 17.2% gaining less weight than the IOM guidelines.
Generally, the authors found that those who gained excessive weight during pregnancy were younger and had longer gestation periods, higher rates of primary Cesarean delivery, and higher BMIs before pregnancy, at delivery, and 7 years after delivery. Not surprisingly, their offspring were heavier, longer, with greater adiposity and "higher umbilical cord blood C-peptide concentrations at birth."
Researchers controlled for pre-pregnancy BMI, family histories, and childhood environmental factors and most results remained statistically significant, the authors said. However, they added that only the association between standardized gestational weight gain and diastolic blood pressure percentile remained significant after adjusting for childhood BMI.
They hypothesized that the association between gestational weight gain and cardiometabolic outcomes in offspring could be attributed to shared familiar genes and behaviors, such as a child inheriting his or her mother's genetic susceptibility to weight gain. Mothers also share similar diets, physical activity levels with their children during early childhood, "which may link greater maternal [gestational weight gain] with [unfavorable] outcomes in the offspring in later life," the authors wrote.
"The fact that the effect on some traits persist despite adjustment for a variety of confounding factors suggest that this association may be independent of shared lifestyle factors or [behavior]," Ma said in an email. "One potential mechanism is a direct effect of the intrauterine exposure on modifying the developmental trajectory of the offspring, for example through epigenetics or other mechanisms. We are currently undertaking research in this area."
Limitations to the study include the self-reported nature of pre-pregnancy weight and an inability to generalize across various races and ethnicities due to the fact that all of the women studied were Asian. Additionally, IOM recommendations used to classify the women as gaining too much or too little gestational weight were based on healthy white women. Lastly, researchers were unable to explore associations using gestational weight gain at different stages of pregnancy because "repeated measures of maternal weight were not recorded in this study."
This study was funded by the National Institute of Child Health and Human Development and the National Institute of Diabetes and Digestive and Kidney Diseases. The HAPO follow-up study at the Hong Kong Center was supported by funding from the General Research Fund of the Research Grants Council of the Hong Kong SAR, China.
The authors disclosed no conflicts of interest.
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Source Reference: Tam C, et al "The impact of maternal gestational weight gain on cardiometabolic risk factors in children" Diabetologia 2018; DOI: 10.1007/s00125-018-4724-x.
Read the original article on Medpage Today: Pregnancy Weight Gain Tied to Kids' Cardiometabolic Risk Factors