RESUMO
Objective: To investigate the association between cesarean section (CS) and postpartum fertility and dysmenorrhea using data from a Japanese insurance registry. Methods: This retrospective cohort study used a data set of patients registered between 2007 and 2021 in an insurance registry comprising specific employee-based health insurance companies in Japan. Of those data sets, we included data from participants who had their first recorded childbirth between 2014 and 2018. The exclusion criteria were any prior deliveries, dysmenorrhea, or complications that would affect the next pregnancy or postpartum dysmenorrhea since 2007. The occurrence of subsequent childbirth and postpartum dysmenorrhea until 2021 was compared between the CS and vaginal delivery (VD) groups using the log-rank test and Cox proportional hazards model with stratification according to age and age matching. Results: This study included 25,984 (5,926 after age matching) and 5,926 participants in the VD and CS groups, respectively. After age matching, the rate of subsequent childbirth was 18.3% and 16.3%, and the rate of postpartum dysmenorrhea was 6.5% and 7.8% in the VD and CS groups, respectively. There were fewer subsequent childbirths in the CS group than in the VD group after age matching in the stratified Cox proportional hazards model (hazard ratio [HR] 95% confidence interval [CI]: 0.86 [0.79-0.94]). The CS group had a significantly higher risk of dysmenorrhea (HR [95% CI]: 1.18 [1.03-1.36]). Conclusions: Although confounding might be existing, our study suggests that CS might be associated with decreased postpartum fertility and increased dysmenorrhea. The medical indications for CS should be carefully determined; post-CS women should be meticulously followed up.
RESUMO
In order to investigate the influence of cholesterol (Ch) and monosialoganglioside (GM1) on the release and subsequent deposition/aggregation of amyloid beta peptide (Abeta)-(1-40) and Abeta-(1-42), we have examined Abeta peptide model membrane interactions by circular dichroism, turbidity measurements, and transmission electron microscopy (TEM). Model liposomes containing Abeta peptide and a lipid mixture composition similar to that found in the cerebral cortex membranes (CCM-lipid) have been prepared. In all, four Abeta-containing liposomes were investigated: CCM-lipid; liposomes with no GM1 (GM1-free lipid); those with no cholesterol (Ch-free lipid); liposomes with neither cholesterol nor GM1 (Ch-GM1-free lipid). In CCM liposomes, Abeta was rapidly released from membranes to form a well defined fibril structure. However, for the GM1-free lipid, Abeta was first released to yield a fibril structure about the membrane surface, then the membrane became disrupted resulting in the formation of small vesicles. In Ch-free lipid, a fibril structure with a phospholipid membrane-like shadow formed, but this differed from the well defined fibril structure seen for CCM-lipid. In Ch-GM1-free lipid, no fibril structure formed, possibly because of membrane solubilization by Abeta. The absence of fibril structure was noted at physiological extracellular pH (7.4) and also at liposomal/endosomal pH (5.5). Our results suggest a possible role for both Ch and GM1 in the membrane release of Abeta from brain lipid bilayers.