Lithium has been used in the treatment of bipolar disorder in pregnant women. However, information on the pharmacokinetics of lithium during perinatal period is scarce.

To study pharmacokinetics of lithium during delivery and in the neonatal period.

A prospective, observational and naturalistic study was conducted at the PERINATAL PSYCHIATRY PROGRAM CLÍNIC-BARCELONA, from 2005 to 2012. We included all consecutive cases of pregnant women with bipolar disorder I or II (n = 22), and on maintenance treatment with lithium monotherapy (n = 13) or polytherapy (n = 9) during pregnancy who elected artificial feeding. Lithium plasma concentrations in maternal blood and umbilical cord were detected. Lithium plasma concentrations in infants (n = 16) at delivery and in the neonatal period were obtained to calculate elimination half-life, which was estimated by lineal regression. Technique: AVL 9180 electrolyte analyser using a lithium-selective electrode (detection limit =0.10 mEq/L).

Women did not fulfil diabetes criteria pre-pregnancy and during pregnancy. Attending to neonatal outcomes, infants exposed to polytherapy had a higher weight at birth (percentils) than those exposed to lithium alone [53.38 (33.40) vs. 70.22 (26.25)]. No statistically significant differences were found in umbilical cord:maternal plasma concentration ratio between those treated with lithium monotherapy and women treated with polytherapy (1.05 vs. 1.08). The lithium mean elimination half-life (SD) in infants was 6.73 (9.12) days.

Lithium crosses placental barrier almost completely. Elimination half-life in neonates exposed to lithium in utero was 6.73 days. Moreover, lithium treatment during pregnancy requires therapeutics monitoring in exposed dyads.

Variables such as the mother's personality, social support, coping strategies and stressful events have been described as risk factors for postpartum depression. Structural Equation Modelling (SEM) analysis was used to examine whether neuroticism, perceived social support, perceived life events, and coping strategies are associated with postpartum depressive symptoms at the 8th and 32nd weeks.

A total of 1626 pregnant women participated in a longitudinal study. Different evaluations were performed 8 and 32 weeks after delivery. Several measures were used: the Edinburgh Postnatal Depression Scale (EPDS), the Diagnostic Interview for Genetic Studies (DIGS), the Eysenck Personality Questionnaire (EPQ-RS), the St. Paul Ramsey life events scale and the Duke-UNC Functional Social Support Questionnaire. The brief COPE scale was used to measure coping strategies. SEM analysis was conducted for all women and in those women with a clinical diagnosis of postpartum depression.

Passive coping strategies were associated with postpartum depressive symptoms at both visits (8th and 32nd weeks). Neuroticism was associated with more passive coping strategies and less active coping strategies. Neuroticism and life stress were positively correlated, and social support was negatively correlated with life stress and neuroticism.

Early identification of potential risk for symptomatology of depression postpartum should include assessment of neuroticism, life events, social support and coping strategies.

Polymorphic variations in the serotonin transporter gene (5-HTT) moderate the depressogenic effects of tryptophan depletion. After childbirth there is a sharp reduction in brain tryptophan availability, thus polymorphic variations in 5-HTT may play a similar role in the post-partum period.

To study the role of 5-HTT polymorphic variations in mood changes after delivery.

One thousand, eight hundred and four depression-free Spanish women were studied post-partum. We evaluated depressive symptoms at 2–3 days, 8 weeks and 32 weeks post-partum. We used diagnostic interview to confirm major depression for all probable cases. Based on two polymorphisms of 5-HTT (5-HTTLPR and STin2 VNTR), three genotype combinations were created to reflect different levels of 5-HTT expression.

One hundred and seventy-three women (12.7%) experienced major depression during the 32-week post-partum period. Depressive symptoms were associated with the high-expression 5-HTT genotypes in a dose–response fashion at 8 weeks post-partum, but not at 32 weeks.

High-expression 5-HTT genotypes may render women more vulnerable to depressive symptoms after childbirth.