gestational weight gain

Summary
This study examines the behavioral and psychological correlates of gestational weight gain patterns. Recommendations for optimal gestational eight gain are based on the pre-pregnancy or baseline body mass indexes. Weight gain significantly below or above the recommendations for one’s BMI can lead to adverse outcomes including low birth weight, increased risk for caesarean delivery, and even childhood obesity. Based on prior literature showing that a multitude of variables may impact gestational weight gain, this study illustrates some of the psychological variables that may be implicated. The authors use a biopsychosocial model, which takes multiple issues into account including biological factors, psychosocial factors, and also health-related behaviors like sleep patterns, nutrition and eating behaviors, and physical activity. The primary research question is which factors have the strongest bearing on gestational weight gain patterns, with the goal of optimizing prenatal care.
Methodology
The researchers rely on an exploratory question and use a prospective cohort multifactorial research design. The dependent variable was gestational weight gain, measured in two ways. The first was a simplistic method of subtracting self-reported pre-pregnancy weight from last measured weight before delivery, and the second was to compare total weight gain with the recommendations of the Institute of Medicine. The authors classified the dependent variable as being either inadequate or excessive.
Independent variables included biological, psychological, and socioeconomic factors. Biological variables included only height. Sociodemographic variables included level of educational attainment, marriage status, and employment status. The authors also classified the participants into binary groups, based on whether the pregnancy was intentional/planned or unplanned. The authors do not explain why they used this variable at the exclusion of others, and do not offer reference to prior literature on whether planned versus unplanned pregnancies has an impact on depression and other psychological variables, let alone weight gain. To measure psychological well-being, the authors use the Perceived Stress Scale, the Prenatal Distress Questionnaire, and the Edinburgh Postpartum Depression Scale, each of which does have a degree of validity and reliability as they have been established in prior literature. Health behaviors were measured in terms of food intake, physical activity, sleeping, and smoking. To perform data analyses, the authors used linear regression models, backwards stepwise models, and simultaneous entry regression.
Population
A convenience sample was culled from the population of women registered with the National Maternity Hospital in Dublin. Research assistants recruited potential participants from the list of booked appointments, and each participant was offered information and informed consent related to the study. Eligibility requirements included being eighteen years of age or older, capable of giving full informed consent, and only expecting a singleton pregnancy. A total of 1229 women were initially invited, and 984 were eligible and completed all the necessary questionnaires. Women with gestational diabetes and women with indeterminate weight information were also excluded from the study, resulting in a total of 799 valid participants whose data was analyzed. Mean age of the participants was 31 years.
Findings
In terms of raw data related to socidemographics, the researchers found that almost all (90%) of the participants lived with the father of their child, and roughly 30% were foreign nationals. Half had higher education degrees, and over half had private health insurance. The research showed that over 62% of the women exceeded the IOM gestational weight gain recommendations. The authors found that biological variables correlated most with the excessive weight gain outcome. Most notably, pre-pregnancy obesity, older age, and shorter stature were biological variables linked to excessive gestational weight gain. These are correlations with statistical significance. Likewise, similar univariate analyses of the sociodemographic variables also showed statistically significant correlations between unintentional pregnancy, absence of health insurance, and employment or financial concerns and inadequate gestational weight gain. Only some of the health behaviors, on the other hand, were linked with gestational weight gain. Specifically, increased food intake and smoking cessation were linked with excessive weight gain versus decreased food intake and smoking. Inadequate sleeping was also linked with inadequate weight gain. Interestingly, the authors found that foreign-born mothers were more likely to have excessive weight gain.
Conclusions
The conclusions are generally justified, particularly with regards to the univariate analyses but also with some of the multivariate analyses taking into account both biological and psychosocial variables. In spite of the potential relevance and impact of this study on prenatal care, there are a few methodological weaknesses in the study that diminish its internal validity. One is that pre-pregnancy weight was measured via self-reports. Also, by classifying the dependent variable in a binary way, by either excessive or inadequate weight gain, the authors do not allow any investigation of nuances or intermediary weight gain. Another weakness in the methodology was that the authors only took height and weight into account as biological variables, instead of also investigating other health variables like blood pressure, and the presence or absence of specific diseases that might impact the metabolism. Also, the means by which behavioral variables were measured were unreliable, particularly with regards to food intake. Food intake was measured via self-reports and only along a progressive style scale where the participant estimated whether their caloric intake during pregnancy was more or less than it was before pregnancy. These methodological weaknesses impede the validity of the results but overall the implications of the study are meaningful on prenatal and perinatal care.




References
Heery, E., Kelleher, C.C., Wall, P.G., et al. (2014). Prediction of gestational weight gain. Public Health Nutrition 18(8): 1488-1498.