The present study sought to examine the association between dietary Ca intake and risk of gestational diabetes mellitus (GDM).

We assessed periconceptional (i.e. before conception and early pregnancy) Ca intake and consumption of foods rich in Ca using an FFQ among 3414 participants in a prospective cohort study. Diagnoses of GDM were abstracted from medical records. We used multivariable generalized linear regression models to derive estimates of relative risk (RR) for GDM and 95 % confidence intervals.

A prospective cohort of women in Seattle and Tacoma, WA, USA.

Women (n 3414).

A total of 169 GDM incident cases were identified in the cohort (4·96 %). Higher dietary Ca intake was inversely, although not statistically significantly, associated with GDM risk. After adjusting for confounders, the RR (95 % CI) for GDM according to successive increasing quartile of Ca intake was 1·00, 0·63 (0·41, 0·98), 0·66 (0·39, 1·11) and 0·57 (0·27, 1·21), respectively, with the lowest quartile as the reference (Ptrend=0·131). Compared with women in the first quartile for Ca intake, women in the higher three quartiles (≥795 v. <795 mg/d) had a 42 % (RR=0·58; 95 % CI 0·38, 0·90; P=0·015) lower GDM risk. GDM risk was inversely associated with low-fat dairy (Ptrend=0·032) and whole grains (Ptrend=0·019) consumption.

These findings suggest that higher levels of periconceptional Ca intake, particularly intake of Ca-rich low-fat dairy products and whole grains, are associated with lower GDM risk.

To investigate associations of maternal periconceptional shellfish, lean fish and fatty fish intake with risk of pregnancy complications.

In this prospective cohort study, we collected information on intake of seafood subtypes using FFQ. We categorized seafood intake into frequencies of <0·2 servings/month, 0·2 servings/month–<0·5 servings/week, 0·5–1·0 servings/week and >1 servings/week. We ascertained gestational hypertension, pre-eclampsia, gestational diabetes and preterm birth diagnoses from medical records. Using generalized linear models with a log link, the Poisson family and robust standard errors, we estimated risk ratios and 95 % confidence intervals across seafood intake categories.

The Omega study, a study of risk factors for pregnancy complications among women recruited from prenatal clinics in Washington State, USA, 1996–2008.

The current study included 3279 participants from the Omega study.

Median (interquartile range) shellfish, lean fish and fatty fish intake was 0·3 (0–0·9), 0·5 (0–1·0) and 0·5 (0·1–1·0) servings/week, respectively. Lean fish intake of >1 servings/week (v. <0·2 servings/month) was associated with a 1·55-fold higher risk of preterm birth (95 % CI 1·04, 2·30) and was not associated with the other pregnancy complications. Higher intake of seafood (total or other subtypes) was not associated with pregnancy complications (separately or combined).

Higher intake of lean fish, but not fatty fish or shellfish, was associated with a higher risk of preterm birth; these findings may have significance for preterm birth prevention. Studies of mechanisms and potential contributing factors (including seafood preparation and nutrient/contaminant content) are warranted.

To examine cross-sectional relationships between plasma vitamin D and cardiometabolic risk factors in young adults.

Data were collected from interviews, physical examinations and biomarker measurements. Total plasma 25-hydroxyvitamin D (25(OH)D) was measured using LC–tandem MS. Associations between 25(OH)D and cardiometabolic risk factors were modelled using weighted linear regression with robust estimates of standard errors.

Individuals born in Jerusalem during 1974–1976.

Participants of the Jerusalem Perinatal Study (n 1204) interviewed and examined at age 32 years. Participants were oversampled for low and high birth weight and for maternal pre-pregnancy obesity.

Mean total 25(OH)D concentration among participants was 21·7 (sd 8·9) ng/ml. Among males, 25(OH)D was associated with homeostatic model assessment of insulin resistance (natural log-transformed, β=−0·011, P=0·004) after adjustment for BMI. However, these associations were not present among females (P for sex interaction=0·005).

We found evidence for inverse associations of 25(OH)D with markers of insulin resistance among males, but not females, in a healthy, young adult Caucasian population. Prospective studies and studies conducted on other populations investigating sex-specific effects of vitamin D on cardiometabolic risk factors are warranted.

We assessed serum homocysteine (tHcy) and folate concentrations among US adolescents before and after fortification of cereal-grain products with folic acid, and associations with demographic, behavioural and physiological factors.

Observational study conducted among participants of a randomized trial.

The Child and Adolescent Trial for Cardiovascular Health (CATCH) study.

Adolescents (n 2445) in grades 8 (pre-fortification, mean age 14 years) and 12 (post-fortification, mean age 18 years).

Average serum concentrations of tHcy, folate and vitamin B6 increased by 17 %, 16 % and 14 %, respectively, while serum concentrations of vitamin B12 decreased by 11 % post-fortification. Folic acid fortification provided, on average, an additional intake of 118 μg folate/d. Male sex (P < 0·0001) and white race (P = 0·0008) were associated with significantly greater increases in tHcy concentration, while increases in BMI (P = 0·006) and serum folate concentration (P < 0·0001) were associated with significant decreases in tHcy concentration. Female sex (P < 0·0001), non-smoking (P < 0·0001), use of multivitamins (P < 0·0001) and higher dietary intake of folate (P = 0·001) were associated with significantly greater increases in serum folate concentrations. From grade 8 to grade 12, the upward age trend in serum tHcy concentration was uninterrupted in its course (P > 0·50); whereas serum folic acid concentration showed a downward trend that incurred a discrete jump upward (17 % higher; P < 0·0001) with fortification. These trends differed significantly for males v. females (P < 0·001 for interaction).

Fortification had a significant impact on improving folate status but not serum tHcy concentrations among US adolescents.