A systematic review and time-response meta-analysis of the optimal timing of elective caesarean sections for best maternal and neonatal health outcomes

Abstract

Background: The rate of caesarean sections (CS) has increased in the last decades to about 30% of births in high income countries. Many CSs are electively planned without an urgent medical reason for mother or child. An early CS though may harm the newborn. Our aim was to evaluate the gestational time point after the 37 + 0 week of gestation (WG) (after prematurity = term) of performing an elective CS with the lowest morbidity for mother and child by assessing the time course from 37 + 0 to 42+ 6 WG. Methods: We performed a systematic literature search in MEDLINE, EMBASE, CENTRAL and CINAHL in November 2018. We included studies that compared different time points of elective CS at term no matter the reason for elective CS. Our primary outcomes were the rate of admissions to the neonatal intensive care unit (NICU), neonatal death and maternal death in early versus late term elective CS. Various binary and dose response random effects meta-analyses were performed. Results: We identified 35 studies including 982,749 women. Except one randomised controlled trial, all studies were cohort studies. We performed a linear time-response meta-analysis on the primary outcome NICU admission on 14 studies resulting in a decrease of the relative risk (RR) to 0.63 (95% CI 0.56, 0.71) from 37 + 0 to 39 + 6 WG. RR for neonatal death showed a decrease to 39 + (0-6) WG (RR 0.59 95% CI 0.43 to 0.83) and increase from then on (RR 2.09 95% CI 1.18 to 3.70) assuming a U-shape course and using a cubic spline model for meta-analysis of four studies. We only identified one study analyzing maternal death resulting in RR of 0.38 (95% CI 0.04 to 3.40) for 37 + 0 + 38 + 6 WG versus ≥39 + 0 WG. Conclusion: Our systematic review showed that elective CS (primary and repeated) before the 39 + 0 WG lead to more NICU admissions and neonatal deaths, although death is rare and increases again after 39 + 6 WG. We did not find enough evidence on maternal outcomes. There is a need for more research, considering maternal outcomes to provide a balanced decision between neonatal and maternal health.

Review of Unsafe Changes in the Practice of Cesarean Section with Analysis of Flaws in the Interpretation of Statistics and the Evidence

“…This review also highlights a few more anomalous and disadvantageous practice-changes regarding this commonest major operation. Studies should be conducted if elective caesarean should be scheduled between 38 ½ and 39 ½ weeks based on the available data about stillbirths, neonatal mortality, and important logistical issues [24][25][26]. The guideline-makers should correct these mistakes without losing any further time.…”

“…A recent systematic review of 35 studies found that all studies were nonrandomized retrospective cohort analyses except for one RCT [23,26]. The systematic review identified a critical to serious risk of bias in all included studies due to the main issues of patient selection, diverse possibilities of confounding, and lack of blinding [26]. None of the studies reported the reasons why women were selected for either group.…”

“…In many hospitals the "39-week rule" was already in place. The review considered that women who had planned caesarean before 39th week were likely to have underlying reasons affecting outcome [26]. The number of healthy women with uncomplicated pregnancies potentially rises in late-term planned caesarean [26].…”

“…The review considered that women who had planned caesarean before 39th week were likely to have underlying reasons affecting outcome [26]. The number of healthy women with uncomplicated pregnancies potentially rises in late-term planned caesarean [26]. Moreover, "weeks" is an arbitrary construct (accident of convention) and we don't have data if neonatal outcomes will be even better if elective caesarean is performed between 38½ and 39½ weeks (approximately).…”

A Systematic Review on the Effectiveness of Implementation Strategies to Postpone Elective Caesarean Sections to ≥39+(0-6) Week of Gestation.

“…Risks for neonates are decreasing from 37+(0-6) WG onwards and there seems to be no increase in risks for mothers until the 39 + 0-6 WG. (17) This shows that the recommendations given before still last. Nevertheless, it is not fully integrated in clinical practice yet.…”