Preeclampsia is one of the leading causes of maternal and neonatal mortality and morbidity worldwide, affecting 2-8% of all pregnancies. Studies suggest a link between complement activation and preeclampsia. The complement system plays an essential role in the innate immunity, leading to opsonization, inflammation, and elimination of potential pathogens. The complement system also provides a link between innate and adaptive immunity and clearance of immune complexes and apoptotic cells. During pregnancy there is increased activity of the complement system systemically. However, locally at the placenta, complement inhibition is crucial for the maintenance of a normal pregnancy. Inappropriate or excessive activation of the complement system at the placenta is likely involved in placental dysfunction, and is in turn associated with pregnancy complications like preeclampsia. Therefore, modulation of the complement system could be a potential therapeutic target to prevent pregnancy complications such as preeclampsia. This review, based on a systematic literature search, gives an overview of the complement system and its activation locally in the placenta and systemically during healthy pregnancies and during complicated pregnancies, with a focus on preeclampsia. Furthermore, this review describes results of animal and human studies with a focus on the complement system in pregnancy, and the role of the complement system in placental dysfunction. Various clinical and animal studies provide evidence that dysregulation of the complement system is associated with placental dysfunction and therefore with preeclampsia. Several drugs are used for prevention and treatment of preeclampsia in humans and animal models, and some of these drugs work through complement modulation. Therefore, this review further discusses these studies examining pharmaceutical interventions as treatment for preeclampsia. These observations will help direct research to generate new target options for prevention and treatment of preeclampsia, which include direct and indirect modulation of the complement system.

Background Reproductive-aged women are, according to American and European guidelines, recommended to avoid pregnancy for 12-24 months after bariatric surgery. Oral contraceptives may have suboptimal efficacy after malabsorptive bariatric procedures. Aim The aim of this study was to assess contraceptive use pre-and postoperatively in women who underwent bariatric surgery in two obesity clinics in The Netherlands. Also, the recall of contraceptive and pregnancy counseling was investigated. Methods A validated questionnaire was performed among women aged 18-45 years who underwent bariatric surgery from October 2017 through August 2018. Results In total, 230 women were eligible for final analysis. Postoperatively, 60% used safe contraception, 16.1% unsafe contraception, and 23.9% no contraception. In this study, 43.7% of women using a potential unsafe contraceptive method preoperatively switched to a safe method of contraception postoperatively (p < 0.0001). Only 62.6% of women confirmed to have received contraceptive counseling, mainly preoperatively. The odds ratio for receiving contraceptive counseling and using safe contraceptive methods compared with not receiving contraceptive counseling was 2.20 (95% CI, 1.27-3.79; p = 0.005). Eighty-three percent confirmed that they have received counseling regarding delaying a pregnancy, and 52.6% were familiar with the recommendation to avoid a pregnancy for 24 months postoperatively. Conclusions In our study, 60% of women are using safe contraception postoperatively. Contraceptive counseling is suboptimal as 62.6% recall receiving counseling. Those who confirmed receiving counseling were more likely to use safe contraception after bariatric surgery. More counseling and monitoring in the postoperative and in the outpatient setting is recommended.