Maternal pre-pregnancy weight and twins’ temperament

Associations between antenatal maternal diet and other health aspects with infant temperament in a large multiethnic cohort study: a path analysis approach

OBJECTIVES

The aim of this study was to assess the association of antenatal maternal dietary patterns (DPs) and other health aspects with infant temperament in a large multiethnic cohort, taking maternal personality and prenatal stress into account.

DESIGN AND METHODS

Using data from 3968 children born in 2009/2010 and their mothers from the Growing Up in New Zealand cohort, infant temperament was assessed at 9 months using the Infant Behavior Questionnaire-Revised Very Short Form. Maternal antenatal diet and other health aspects were assessed antenatally. Maternal DPs (n=4) were derived using principal components analysis based on food intake reported on a 44-item food frequency questionnaire. Path analyses investigated factors associated with infant temperament, namely maternal personality, prenatal maternal stress, DPs and other health aspects, including potential inter-relations and mediating effects.

RESULTS

Women who scored higher in the fusion DP (standardised beta (β)=0.05; 95% CI 0.02 to 0.09) and healthy DP (β=0.05; 95% CI 0.02 to 0.09), who exercised more (β=0.04; 95% CI 0.01 to 0.07), and who drank less alcohol (β=-0.05; 95% CI -0.08 to -0.02) were more likely to have infants with an overall less difficult temperament. Sex-specific differences were found in the associations between maternal DP and infant temperament. Maternal personality and prenatal stress were significantly associated with all dimensions of infant temperament. The strongest predictors for a more difficult temperament were prenatal stress (β=0.12; 95% CI 0.08 to 0.15) and the personality dimensions neuroticism (β=0.10; 95% CI 0.07 to 0.14) and extraversion (β=-0.09; 95% CI -0.12 to -0.06).

CONCLUSIONS

Associations of antenatal maternal diet and health aspects with infant temperament were statistically significant but small. While they should not be overinterpreted as being deterministic, the findings of this study support the link between maternal modifiable health-related behaviours and infant temperament outcomes.

Measured weight in early pregnancy is a valid method for estimating pre-pregnancy weight

Estimation of pre-pregnancy weight is difficult because measurements taken before pregnancy are rarely available. No studies have compared various 'proxy' measures using recalled weight or based on early pregnancy weight with actual measurements of pre-pregnancy weight. The Southampton Women's Survey recruited women during 1998-2002 who were not pregnant. Data on 198 women with an estimated date of conception within 3 months of recruitment were analysed. Three proxy measures were considered: (1) recalled pre-pregnancy weight obtained during early pregnancy, (2) measured weight in early pregnancy and (3) estimated pre-pregnancy weight using a published model. Mean (standard deviation) recalled weight was 1.65 (3.03) kg lighter than measured pre-pregnancy weight, while early pregnancy weight and weights from the published model were 0.88 (2.34) and 0.88 (2.33) kg heavier, respectively. The Bland-Altman limits of agreement for recalled weight were -7.59 to 4.29 kg, wider than those for the early pregnancy weight: -3.71 to 5.47 kg and the published model: -3.68 to 5.45 kg. For estimating pre-pregnancy weight, we recommend subtraction of 0.88 kg from early pregnancy weight or the published model, or addition of 1.65 kg to recalled weight. Estimates of pre-pregnancy body mass index and gestational weight gain categories were very similar when using early pregnancy and published model weights, but they differed from those using recalled weight. Our findings indicate that calculations of first trimester weight gain using recalled weight must be treated cautiously, and a measured weight in early pregnancy provides a more precise assessment of pre-pregnancy weight than recalled weight.