Background Preeclampsia, a new-onset hypertensive disorder of pregnancy, is associated with lifetime cardiovascular disease risk, but less is known about risk after other pregnancy-related hypertension. Methods and Results The Northern Finland Birth Cohort 1966 included all expected births from 1 year (N=12 055 women). Blood pressure measurements and other prospective data were determined from prenatal care records and questionnaires for 10 314 women. Subsequent diagnoses were ascertained from Finnish registries (average follow-up, 39.4 years). Adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) estimate risks in hypertensive women compared with normotensive women. Hypertension during pregnancy was associated with increased risk of subsequent cardiovascular disease and arterial hypertension. Women with chronic hypertension and superimposed preeclampsia/eclampsia had high risk for future diseases. Gestational hypertension was associated with increased risk of ischemic heart disease (HR, 1.44 [95% CI, 1.24–1.68]), myocardial infarcts (HR, 1.75 [95% CI, 1.40–2.19]), myocardial infarct death (HR, 3.00 [95% CI, 1.98–4.55]), heart failure (HR, 1.78 [95% CI, 1.43–2.21]), ischemic stroke (HR, 1.59 [95% CI, 1.24–2.04]), kidney disease (HR, 1.91 [95% CI, 1.18–3.09]), and diabetes mellitus (HR, 1.52 [95% CI, 1.21–1.89]). Isolated systolic hypertension was associated with increased risk of myocardial infarct death (HR, 2.15 [95% CI, 1.35–3.41]), heart failure (HR, 1.43 [95% CI, 1.13–1.82]), and diabetes mellitus (HR, 1.42 [95% CI, 1.13–1.78]), whereas isolated diastolic hypertension was associated with increased risk of ischemic heart disease (HR, 1.26 [95% CI, 1.05–1.50]). Results were similar in nonsmoking women aged <35 years with normal weight and no diabetes mellitus during pregnancy. Conclusions Elevated blood pressure during pregnancy, regardless of type and even without known risk factors, signals high risk of later cardiovascular disease, chronic kidney disease, and diabetes mellitus. Clinical monitoring, risk factor evaluation, and early intervention could benefit women with hypertension in pregnancy.

IMPORTANCE Maternal hypothyroidism and hyperthyroidism are risk factors for preterm birth. Milder thyroid function test abnormalities and thyroid autoimmunity are more prevalent, but it remains controversial if these are associated with preterm birth. OBJECTIVE To study if maternal thyroid function test abnormalities and thyroid autoimmunity are risk factors for preterm birth. DATA SOURCES AND STUDY SELECTION Studies were identified through a search of the Ovid MEDLINE, EMBASE, Web of Science, the Cochrane Central Register of Controlled Trials, and Google Scholar databases from inception to March 18, 2018, and by publishing open invitations in relevant journals. Data sets from published and unpublished prospective cohort studies with data on thyroid function tests (thyrotropin [often referred to as thyroid-stimulating hormone or TSH] and free thyroxine [FT 4 ] concentrations) or thyroid peroxidase (TPO) antibody measurements and gestational age at birth were screened for eligibility by 2 independent reviewers. Studies in which participants received treatment based on abnormal thyroid function tests were excluded. DATA EXTRACTION AND SYNTHESIS The primary authors provided individual participant data that were analyzed using mixed-effects models. MAIN OUTCOMES AND MEASURES The primary outcome was preterm birth (<37 weeks' gestational age). RESULTS From 2526 published reports, 35 cohorts were invited to participate. After the addition of 5 unpublished data sets, a total of 19 cohorts were included. The study population included 47 045 pregnant women (mean age, 29 years; median gestational age at blood sampling, 12.9 weeks), of whom 1234 (3.1%) had subclinical hypothyroidism (increased thyrotropin concentration with normal FT 4 concentration), 904 (2.2%) had isolated hypothyroxinemia (decreased FT 4 concentration with normal thyrotropin concentration), and 3043 (7.5%) were TPO antibody positive; 2357 (5.0%) had a preterm birth. The risk of preterm birth was higher for women with subclinical hypothyroidism than euthyroid women (6.1% vs 5.0%, respectively; absolute risk difference, 1.4% [95% CI, 0%-3.2%]; odds ratio [OR], 1.29 [95% CI, 1.01-1.64]). Among women with isolated hypothyroxinemia, the risk of preterm birth was 7.1% vs 5.0% in euthyroid women (absolute risk difference, 2.3% [95% CI, 0.6%-4.5%]; OR, 1.46 [95% CI, 1.12-1.90]). In continuous analyses, each 1-SD higher maternal thyrotropin concentration was associated with a higher risk of preterm birth (absolute risk difference, 0.2% [95% CI, 0%-0.4%] per 1 SD; OR, 1.04 [95% CI, 1.00-1.09] per 1 SD). Thyroid peroxidase antibody-positive women had a higher risk of preterm birth vs TPO antibody-negative women (6.6% vs 4.9%, respectively; absolute risk difference, 1.6% [95% CI, 0.7%-2.8%]; OR, 1.33 [95% CI, 1.15-1.56]). CONCLUSIONS AND RELEVANCE Among pregnant women without overt thyroid disease, subclinical hypothyroidism, isolated hypothyroxinemia, and TPO antibody positivity were significantly associated with higher risk of preterm birth. These results provide i...

These gestational age-specific reference intervals for thyroid hormones provide a framework for clinical decision making. Overweight and obesity are increasing problems among fertile women and they are associated with possibility of thyroid dysfunction during pregnancy.

Studies on hypothyroidism and hyperthyroidism implicate that adequate maternal thyroid hormone availability is required for optimal fetal growth and development. Studies on the association of mild thyroid function test abnormalities with birth weight report heterogeneous results. Some studies indicate that high FT4 concentrations are associated with lower birth weight which could have implications for the treatment target in women already on levothyroxine therapy. We searched Medline (Ovid), Embase.com, Web-of-Science, Cochrane CENTRAL and Google Scholar up to March 18 th , 2018 and collected data on serum thyroid function tests and antibody status during pregnancy and birth weight from prospective cohort studies including treatment-naïve pregnant women.