Effects of early aspirin therapy on utero-placental hemodynamics in patients at risk of preeclampsia.

OBJECTIVES: To evaluate the effects of early aspirin therapy on the mean pulsatility index of both uterine arteries (utA PI) at 1st and 2nd trimester in women at risk of preeclampsia (PE). METHODS: Uterine artery (utA) blood flow characteristics were obtained in 315 women, 73 women at risk for PE and early aspirin treatment (group 1), 124 without specific risk factors and no aspirin treatment (group 2) and 118 women with manifest PE (group 3). Mean utA PI of group 1 and group 2 were compared within and between the groups at the 1st and 2nd trimester time points. Furthermore, values at 2nd trimester were compared with those of group 3. Observed to expected mean utA PI ratio (O/E ratio) were calculated for comparison between the groups. RESULTS: Mean utA PI of group 1 was significantly higher in the 1st trimester compared to group 2 (1.74 vs. 1.47, p = .0117). In the 2nd trimester mean PI decreased significantly in both groups from 1.74 to 1.16 in group 1 and from 1.47 to 0.90 in group 2 (p < .0001). Nevertheless, the difference between the groups was significantly higher in the 2nd trimester than in the 1st trimester (0.29 vs. 0.27, p < .001). Correction for gestational age by analyzing mean utA O/E ratios showed a comparable pattern with a significantly decrease in both groups (1.40 to 1.10 in group 1 and 1.18 to 0.78 in group 2, p < .0001), but a significant higher decrease in the 2nd trimester in group 2 (0.31 vs.0.22, p < 0001).The prevalence of PE was 15.1% (11/73) in group 1 (4 early/7 late onset PE) and 4.7% (6/124) in group 2 (1 early/5 late onset). Mean utA PI and O/E ratio obtained in the 2nd trimester were higher in all PE cases with no significant difference between early and late onset PE (1.49/1.57 and 1.25/1.36 in group 1 and 0.80/0.97 and 0.77/0.99 in group 2). However, mean utA PI and O/E ratio decreased in all cases without PE in both groups, whereas mean utA PI was 1,37 and O/E-ratio was 1,29 in patients with manifest PE at admission, with significantly higher values in early onset than in late onset PE (1.45/1.31 vs. 1.07/1.02, p < .0001). CONCLUSIONS: Our results show that early aspirin treatment leads to a decrease of elevated mean utA PI between 1st and 2nd trimester in patients at elevated risk for PE which is inferior to the decrease observed in women at standard risk for PE. While aspirin improves trophoblast invasion during early second trimester, vascular resistance remains well above average levels. Limited vascular remodeling capacity in the utero-placental perfusion area seems to be the explanation why aspirin does not abrogate PE in all women and has little effect on birth weight. Another explanation might be that a dose of 100 mg aspirin was used as compared to the 150 mg which is recommended today. Our findings underscore the need to study the effects of intervention already during the early stages of trophoblast invasion in the first trimester.

Obstetrician involvement in planned midwife-led births: a cohort study in an obstetric department of a University Hospital in Switzerland.

BACKGROUND: Healthy women with low risk singleton pregnancies are offered a midwife-led birth model at our department. Exclusion criteria for midwife-led births include a range of abnormalities in medical history and during the course of pregnancy. In case of complications before, during or after labor and birth, an obstetrician is involved. The purpose of this study was 1) to evaluate the frequency of and reasons for secondary obstetrician involvement in planned midwife-led births and 2) to assess the maternal and neonatal outcome. METHODS: We analyzed a cohort of planned midwife-led births during a 14 years period (2006-2019). Evaluation included a comparison between midwife-led births with or without secondary obstetrician involvement, regarding maternal characteristics, birth mode, and maternal and neonatal outcome. Statistical analysis was performed by unpaired t-tests and Chi-square tests. RESULTS: In total, there were 532 intended midwife-led births between 2006 and 2019 (2.6% of all births during this time-period at the department). Among these, 302 (57%) women had spontaneous vaginal births as midwife-led births. In the remaining 230 (43%) births, obstetricians were involved: 62% of women with obstetrician involvement had spontaneous vaginal births, 25% instrumental vaginal births and 13% caesarean sections. Overall, the caesarean section rate was 5.6% in the whole cohort of women with intended midwife-led births. Reasons for obstetrician involvement primarily included necessity for labor induction, abnormal fetal heart rate monitoring, thick meconium-stained amniotic fluid, prolonged first or second stage of labor, desire for epidural analgesia, obstetrical anal sphincter injuries, retention of placenta and postpartum hemorrhage. There was a significantly higher rate of primiparous women in the group with obstetrician involvement. Arterial umbilical cord pH < 7.10 occurred significantly more often in the group with obstetrician involvement, while 5' Apgar score < 7 did not differ significantly. The overall transfer rate of newborns to neonatal intensive care unit was low (1.3%). CONCLUSION: A midwife-led birth in our setting is a safe alternative to a primarily obstetrician-led birth, provided that selection criteria are being followed and prompt obstetrician involvement is available in case of abnormal course of labor and birth or postpartum complications.