The effect of maternal characteristics and gestational diabetes on birthweight

Abstract

Objective To examine the effect of maternal characteristics, including advancing maternal age, body mass index (BMI), racial origin and development of gestational diabetes mellitus (GDM), on birthweight and the interactions between these factors.Design Retrospective analysis of prospectively collected data.Setting Fifteen maternity units in North West London, between 1988 and 2000.Population A cohort of 130 549 pregnant women.Methods Multivariate regression analysis.Outcome measures Birthweight z-scores in non-GDM and GDM groups within three main racial groups (white European, black and South Asian women).Results Babies born to women with GDM were heavier compared with those born to women with no GDM in all racial groups. In black women with GDM the birthweight z-scores were 0.805 higher, in South Asian women the scores were 0.618 higher and in white European women the scores were 0.437 higher, compared with the respective non-GDM group (P < 0.001 for both comparisons versus white European women), and these differences were much greater at high rather than at low maternal BMIs. Advancing maternal age, increasing BMI, highest diastolic blood pressure, Castair's index, racial group and presence of GDM or smoking were each, individually, significantly associated with birthweight z-scores (P < 0.001 for all variables). After adjusting for possible confounding factors, BMI was positively associated with birthweight z-scores within all racial groups (P < 0.001 for all), irrespective of glycaemic status, but its effect was much greater in women with GDM, particularly in those of non-White origin. After adjusting for possible confounding factors, advancing maternal age was only positively associated with birthweight in women of white European and South Asian racial origin who did not suffer from GDM (P < 0.001 for both).Conclusion Gestational diabetes mellitus strongly accentuates the effect of maternal BMI on birthweight, especially within nonwhite populations.

Adiposity and hyperglycaemia in pregnancy and related health outcomes in European ethnic minorities of Asian and African origin: a review

“…When assessed together, both maternal hyperglycaemia and obesity were independently associated with increased adiposity in the newborn (140), and their combination had a greater impact than either one alone. However, recent studies have found that the influence of maternal obesity and GDM seemed to be stronger in ethnic minority groups than in groups with European ancestral origin (141, 142) and that the combined effects were particularly strong in these groups.…”

Are pregnancy outcomes associated with risk factor reporting in routinely collected perinatal data?

“…• smoking when infants were small or preterm 10 • maternal hypertension among preterm births 11 • maternal diabetes when infants were large 12 • instrumental birth (forceps or vacuum) among women who experienced perineal trauma 13 • induction among women who required regional analgesia 14 • infant resuscitation (intermittent positive pressure respiration, bag and mask or intubation, or external cardiac massage and ventilation) when Apgar5 ,7.…”

Fetal Growth and Subsequent Maternal Risk of Colorectal Cancer

“…We were able to examine the specific components of birth weight—fetal growth and gestational age—while adjusting for potential confounders including maternal BMI and diabetes. Obese women deliver heavier babies on average (28, 29), and obesity is associated with a modestly increased risk of colorectal cancer (30), although this association has been more evident among men and is not consistently found among women (48, 49). Similarly, diabetic mothers also deliver heavier babies on average (29), and diabetes has been associated with a modestly increased risk of colorectal cancer (31).…”

“…The following variables were examined as adjustment variables or predictors of interest: maternal age at delivery (modeled simultaneously as a continuous variable and categorical variable [<25, 25-29, 30-34, ≥35 years] to allow for a non-linear effect); date of delivery (included to adjust for follow-up time, and modeled simultaneously as a continuous variable and categorical variable by decade to allow for a non-linear effect); fetal growth of the offspring (a standardized fetal growth variable defined as the number of SD from the mean birth weight for gestational age and sex based on a Swedish reference growth curve (26), modeled alternatively as a categorical [<−1; −1 to <1; ≥1 SD] and continuous variable); gestational age at birth of the offspring (based primarily on maternal report of last menstrual period in the 1970s, at which time ultrasound estimation was gradually introduced until it was used exclusively starting in the 1990s; modeled alternatively as a categorical [<34, 34-36, 37-41, ≥42 weeks] and continuous variable); multiple gestation (singleton vs. twin or higher order); maternal parity (1, 2, 3, ≥4); maternal pre-pregnancy body mass index (BMI, modeled alternatively as a categorical [<18.5, 18.5-24.9, 25.0-29.9, ≥30.0] and continuous variable; included because high BMI has been associated with delivering a high birth weight infant (28, 29) and increased risk of colorectal cancer (30)); maternal diabetes (yes or no, identified by any inpatient or outpatient diagnosis of diabetes mellitus prior to delivery, using the Swedish Hospital Registry which includes all inpatient diagnoses from the six most populous counties of southern Sweden since 1964 and nationwide since 1987, and the Swedish Outpatient Registry which includes all outpatient diagnoses nationwide since 2001; included because diabetes has been associated with delivering a high birth weight infant (29) and increased risk of colorectal cancer (31)); maternal education level (compulsory high school or less [≤9 years], practical high school or some theoretical high school [10-11 years], theoretical high school and/or some college [12-14 years], college and/or post-graduate study [≥15 years]); maternal marital status (married/cohabiting, never married, widowed/divorced); and maternal country of birth (Sweden, other Western countries [Europe, U.S., Canada, Australia, New Zealand], other non-Western countries).…”