Maternal depression during pregnancy increases the risk for adverse developmental outcomes in children. However, the underpinning biological mechanisms remain unknown. We tested whether depression was associated with levels of and change in the inflammatory state during pregnancy, if early pregnancy overweight/obesity or diabetes/hypertensive pregnancy disorders accounted for/mediated these effects, and if depression added to the inflammation that typically accompanies these conditions.

We analyzed plasma high-sensitivity C-reactive protein (hsCRP) and glycoprotein acetyls at three consecutive stages during pregnancy, derived history of depression diagnoses before pregnancy from Care Register for Healthcare (HILMO) (N = 375) and self-reports (N = 347) and depressive symptoms during pregnancy using the Center for Epidemiological Studies Depression Scale completed concurrently to blood samplings (N = 295). Data on early pregnancy body mass index (BMI) and diabetes/hypertensive pregnancy disorders came from medical records.

Higher overall hsCRP levels, but not change, during pregnancy were predicted by history of depression diagnosis before pregnancy [HILMO: mean difference (MD) = 0.69 standard deviation (s.d.) units; 95% confidence interval (CI) 0.26–1.11, self-report: MD = 0.56 s.d.; 95% CI 0.17–0.94] and higher depressive symptoms during pregnancy (0.06 s.d. per s.d. increase; 95% CI 0.00–0.13). History of depression diagnosis before pregnancy also predicted higher overall glycoprotein acetyls (HILMO: MD = 0.52 s.d.; 95% CI 0.12–0.93). These associations were not explained by diabetes/hypertensive disorders, but were accounted for and mediated by early pregnancy BMI. Furthermore, in obese women, overall hsCRP levels increased as depressive symptoms during pregnancy increased (p = 0.006 for interaction).

Depression is associated with a proinflammatory state during pregnancy. These associations are mediated by early pregnancy BMI, and depressive symptoms during pregnancy aggravate the inflammation related to obesity.

Synthetic glucocorticoids, to enhance fetal maturation, are a standard treatment when preterm birth before 34 gestational weeks is imminent. While morbidity- and mortality-related benefits may outweigh potential neurodevelopmental harms in children born preterm (<37 gestational weeks), this may not hold true when pregnancy continues to term (⩾37 gestational weeks). We studied the association of antenatal betamethasone exposure on child mental health in preterm and term children.

We included 4708 women and their children, born 2006–2010, from the Prediction and Prevention of Pre-eclampsia and Intrauterine Growth Restriction Study with information on both antenatal betamethasone treatment and child mental and behavioral disorders from the Finnish Hospital Discharge Register from the child's birth to 31 December 2016. Additional follow-up data on mother-reported psychiatric problems and developmental milestones were available for 2640 children at 3.5 (s.d. = 0.07) years-of-age.

Of the children, 187 were born preterm (61 betamethasone-exposed) and 4521 at term (56 betamethasone-exposed). The prevalence of any mental and behavioral, psychological development, emotional and behavioral, and comorbid disorders was higher in the betamethasone-exposed, compared to non-exposed children [odds ratio 2.76 (95% confidence interval 1.76–4.32), 3.61 (2.19–5.95), 3.29 (1.86–5.82), and 6.04 (3.25–11.27), respectively]. Levels of psychiatric problems and prevalence of failure to meet the age-appropriate development in personal-social skills were also higher in mother-reports of betamethasone-exposed children. These associations did not vary significantly between preterm and term children.

Antenatal betamethasone exposure may be associated with mental health problems in children born preterm and in those who end up being born at term.

Previous studies have linked maternal obesity with depressive symptoms during and after pregnancy. It remains unknown whether obesity associates with consistently elevated depressive symptoms throughout pregnancy, predicts symptoms postpartum when accounting for antenatal symptoms, and if co-morbid hypertensive and diabetic disorders add to these associations. We addressed these questions in a sample of Finnish women whom we followed during and after pregnancy.

Early pregnancy body mass index, derived from the Finnish Medical Birth Register and hospital records in 3234 PREDO study participants, was categorized into underweight (<18.5 kg/m2), normal weight (18.5–24.99 kg/m2), overweight (25–29.99 kg/m2), and obese (⩾30 kg/m2) groups. The women completed the Center for Epidemiological Studies Depression Scale biweekly during pregnancy, and at 2.4 (s.d. = 1.2) and/or 28.2 (s.d. = 4.2) weeks after pregnancy.

In comparison to normal weight women, overweight, and obese women reported higher levels of depressive symptoms and had higher odds of clinically significant depressive symptoms during (23% and 43%, respectively) and after pregnancy (22% and 36%, respectively). Underweight women had 68% higher odds of clinically significant depressive symptoms after pregnancy. Overweight and obesity also predicted higher depressive symptoms after pregnancy in women not reporting clinically relevant symptomatology during pregnancy. Hypertensive and diabetic disorders did not explain or add to these associations.

Maternal early pregnancy overweight and obesity and depressive symptoms during and after pregnancy are associated. Mental health promotion should be included as an integral part of lifestyle interventions in early pregnancy obesity and extended to benefit also overweight and underweight women.

A non-optimal foetal environment, reflected in smaller birth size and shorter duration of gestation, is a risk factor for compromised health later in life.

To examine whether smaller birth size and shorter gestation predict depressive symptoms.

A total of 1371 members of a cohort born between 1934 and 1944 at term (259–294 days' gestation) in Helsinki, Finland, completed the Beck Depression Inventory (BDI) and the Center for Epidemiological Studies Depression scale (CES–D) at an average age of 61.5 years (BDI) and 63.4 years (BDI and CES–D).

Gestational length predicted depressive symptoms linearly and independently of gender and birth weight: per day decrease in gestational length, depressive symptoms scores increased by 0.8-0.9% (95% CI 0.2-1.4, P<0.009). Weight, length and head circumference at birth showed no linear association with depression, adjusted for gender and gestational length. The results did not change when further controlled for socioeconomic characteristics at birth and in adulthood, age and body mass index in adulthood.

Susceptibility to depressive symptoms may relate to shorter length of gestation.