Aim: To determine the differences in hemoglobin (Hb) levels in the first 2 days after birth in uncomplicated monochorionic twins in relation to birth order and mode of delivery. Methods: All consecutive uncomplicated monochorionic pregnancies with two live-born twins delivered at our center were included in this retrospective study. We recorded Hb levels at birth and on day 2, and analyzed Hb levels in association with birth order, mode of delivery, and time interval between delivery of twin 1 and 2. Results: A total of 290 monochorionic twin pairs were analyzed, including 171 (59%) twins delivered vaginally and 119 (41%) twins born by cesarean section (CS). In twins delivered vaginally, mean Hb levels at birth and on day 2 were significantly higher in second-born twins compared to first-born twins: 17.8 versus 16.1 g/dL and 18.0 versus 14.8 g/dL, respectively (p < .01). Polycythemia was detected more often in second-born twins (12%, 20/166) compared to first-born twins (1%, 2/166; p < .01). Hb differences within twin pairs delivered by CS were not statistically or clinically significant. We found no association between inter-twin delivery time intervals and Hb differences. Conclusions: Second-born twins after vaginal delivery have higher Hb levels and more often polycythemia than their co-twin, but not when born by CS.

Breast milk constitutes one of the most important sources of postnatal microbes. However, the influence of perinatal factors on the milk microbiome is still poorly understood. The aim of our study was to assess the impact of mode of delivery on the microbiome composition and diversity present in breast milk of healthy mothers. Mature milk samples (n=10) were taken from mothers after 1 month of exclusively breastfeeding. Microbiomes from milk samples were analyzed with 16S ribosomal RNA gene pyrosequencing and targeted quantitative polymerase chain reaction (PCR). Despite inter-individual variability in bacterial composition, The Principal Coordinates Analysis clearly separated milk microbiome from mothers with vaginal delivery (n=6) from those who undergo C-section (n=4). In addition, higher bacterial diversity and richness was found in milk samples from vaginal deliveries. Quantitative PCR data showed that higher levels of Bifidobacterium spp. were related significantly to lower levels of Staphylococcus spp. Despite the low sample size, our data suggest that mode of delivery has an important impact on milk microbiome composition. Further studies with larger sample sizes are needed to confirm these results and to understand the biological effects of C-section associated microbes on infant’s health.

Low maternal vitamin D levels have been associated with adverse pregnancy outcome. A recent study has suggested that low maternal vitamin D levels at the time of delivery are also associated with an almost fourfold increase in caesarean section risk. The aim of the present study was to investigate whether there is a difference in maternal serum 25-hydroxyvitamin D (25(OH)D) levels at 11–13 weeks' gestation according to the mode of delivery. Maternal serum 25(OH)D levels were measured at 11–13 weeks' gestation in 995 singleton pregnancies resulting in the birth of phenotypically normal neonates at term. The measured 25(OH)D levels were adjusted for maternal age, BMI, racial origin, smoking, method of conception and season of blood testing, and the adjusted levels (multiple of the median; MoM) were compared between those who subsequently delivered vaginally and those that delivered by caesarean section. Delivery was vaginal in 79·6 % of cases, by emergency caesarean section in 11·6 % and by elective caesarean section in 8·8 %. The median 25(OH)D level in our population was 46·82 (interquartile range (IQR) 27·75–70·13) nmol/l. The adjusted maternal median 25(OH)D levels in the emergency and elective caesarean section groups (0·99, IQR 0·71–1·46 MoM and 0·96, IQR 0·73–1·27 MoM, respectively) were not significantly different from the vaginal delivery group (0·99, IQR 0·71–1·33 MoM; P = 0·53 and P = 0·81, respectively). First-trimester maternal serum 25(OH)D levels are similar between women who subsequently have a vaginal delivery and those who deliver by elective or emergency caesarean section.

A case is reported of a transfusion syndrome in a triplet pregnancy with intrauterine death of two of the fetuses. This is an exceptional occurrence in a triplet pregnancy and raises the problem of the management of multiple pregnancies associated with the death of one or more of the fetuses. The problem of the method of delivery and the complications arising in triplet dizygotic pregnancies is discussed.

No consensus exists for the optimal mode of delivery for twin fetuses. Opinions vary by type of institution (university medical center vs community hospital), country or continent (North America vs Western Europe) and personal preference of individual physicians. This article lists clinical considerations in arriving at the decision and presents them in the form of a decision tree.