The case-cohort study technique elucidated the difference in the risk factors for placental abruption and placenta previa.

BackgroundThe adverse effects of maternal smoking on the health of pregnant women have been examined mostly on a disease-by-disease basis. The aims of this study were to evaluate simultaneously the effects of smoking during pregnancy on various obstetric complications, using data from a large medical database, and to investigate the expediency of using a case-cohort design for such an analysis.MethodsA case-cohort study was conducted within the Japan Perinatal Registry Network database. Perinatal information on infant deliveries was entered into the database at 125 medical centers in Japan. The base population of the study was 180 855 pregnant women registered in the database from 2001 through 2005. The outcome measures were the incidences of 11 different obstetric complications. Logistic regression models were used to estimate age-adjusted risk ratios (aRRs) and relative excess incidence proportions (REIs).ResultsThe overall prevalence of smoking during pregnancy was 5.8% in the base cohort, and the prevalence was higher among younger women. A comparison of the cases and control cohort showed that smokers during pregnancy had statistically significant higher risks for preterm rupture of the membrane (aRR: 1.67, 95% confidence interval [CI]: 1.43–1.96; REI: 40.2%, 95% CI: 29.9%–49.1%), chorioamnionitis (1.65, 1.36–2.00; 39.4%, 26.4%–50.0%), incompetent cervix (1.63, 1.35–1.96; 38.5%, 25.8%–49.1%), threatened premature delivery (1.38, 1.17–1.64; 27.7%, 14.5%–38.9%), placental abruption (1.37, 1.10–1.72; 27.1%, 8.8%–41.7%), and pregnancy-induced hypertension (1.20, 1.01–1.41; 16.4%, 1.2%–29.3%).ConclusionsMaternal smoking was associated with a number of obstetric complications. This highlights the importance of smoking cessation during pregnancy. In addition, case-cohort analysis proved useful in estimating RRs for multiple outcomes in a large database.

The effect of maternal age differs for each obstetrical complication, and thus, it is important to understand these differences for management of individual pregnant patients.

Duchenne muscular dystrophy is an X-linked recessive genetic disease characterized by severe skeletal muscular degeneration. The placenta is considered to be a promising candidate cell source for cellular therapeutics because it contains a large number of cells and heterogenous cell populations with myogenic potentials. We analyzed the myogenic potential of cells obtained from six parts of the placenta, that is, umbilical cord, amniotic epithelium, amniotic mesoderm, chorionic plate, villous chorion, and decidua basalis. In vitro cells derived from amniotic mesoderm, chorionic plate, and villous chorion efficiently transdifferentiate into myotubes. In addition, in vivo implantation of placenta-derived cells into dystrophic muscles of immunodeficient mdx mice restored sarcolemmal expression of human dystrophin. Differential contribution to myogenesis in this study may be attributed to placental portion-dependent default cell state. Molecular taxonomic characterization of placenta-derived maternal and fetal cells in vitro will help determine the feasibility of cell-based therapy.

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