Freestanding midwifery units versus obstetric units: does the effect of place of birth differ with level of social disadvantage?

Abstract

BackgroundSocial inequity in perinatal and maternal health is a well-documented health problem even in countries with a high level of social equality. We aimed to study whether the effect of birthplace on perinatal and maternal morbidity, birth interventions and use of pain relief among low risk women intending to give birth in two freestanding midwifery units (FMU) versus two obstetric units in Denmark differed by level of social disadvantage.MethodsThe study was designed as a cohort study with a matched control group. It included 839 low-risk women intending to give birth in an FMU, who were prospectively and individually matched on nine selected obstetric/socio-economic factors to 839 low-risk women intending OU birth. Educational level was chosen as a proxy for social position. Analysis was by intention-to-treat.ResultsWomen intending to give birth in an FMU had a significantly higher likelihood of uncomplicated, spontaneous birth with good outcomes for mother and infant compared to women intending to give birth in an OU. The likelihood of intact perineum, use of upright position for birth and water birth was also higher. No difference was found in perinatal morbidity or third/fourth degree tears, while birth interventions including caesarean section and epidural analgesia were significantly less frequent among women intending to give birth in an FMU. In our sample of healthy low-risk women with spontaneous onset of labour at term after an uncomplicated pregnancy, the positive results of intending to give birth in an FMU as compared to an OU were found to hold for both women with post-secondary education and the potentially vulnerable group of FMU women without post-secondary education. In all cases, women without post-secondary education intending to give birth in an FMU had comparable and, in some respects, more favourable outcomes when compared to women with the same level of education intending to give birth in an OU. In this sample of low-risk women, we found that the effect of intended place on birth outcomes did not differ with women’s level of education.ConclusionFMU care appears to offer important benefits for birthing women with no additional risk to the infant. Both for women with and without post-secondary education, intending to give birth in an FMU significantly increased the likelihood of a spontaneous, uncomplicated birth with good outcomes for mother and infant compared to women intending to give birth in an OU. All women should be provided with adequate information about different care models and supported in making an informed decision about the place of birth.

Maternal Outcomes in Birth Centers: An Integrative Review of the Literature

“…The most common study design was a matched cohort comparison. Eleven of the reviewed articles compared a cohort of women planning or beginning labor in the birth center with a similar group of women in the hospital . Six articles (4 from analyzing a single dataset) reported cohort studies of freestanding birth center care that did not employ a matched comparison group .…”

“…Six articles (4 from analyzing a single dataset) reported cohort studies of freestanding birth center care that did not employ a matched comparison group . Cohort studies used a prospective design in 13 articles based on 7 datasets . There were 5 retrospective cohort studies .…”

“…Women who are transferred after this initial intrapartum assessment but prior to admission (known as a preadmit intrapartum transfer in 2 studies), are included in the intrapartum transfer data of some but not all studies, affecting the ability to compare rates across studies. Twelve articles reported intrapartum transfer rates as a ratio of women transferred following admission in labor to all women admitted . Four articles calculated intrapartum transfer rates from a denominator of women planning birth center birth at the beginning of labor .…”

Are freestanding midwifery units a safe alternative to obstetric units for low-risk, primiparous childbirth? An analysis of effect differences by parity in a matched cohort study

“…However, post hoc recalculation revealed only a modest loss of statistical power. Additional details are described in previous publications [37, 48]. As for the subgroup analysis presented here, primiparous women constituted only 25.6% of all participants; it may thus be questioned whether the statistical power of our study is sufficient to detect true differences between subgroups.…”

“…As the primary outcome for this analysis of effect modification by parity, we chose the composite outcome “a spontaneous, uncomplicated birth leaving both mother and infant in good condition”, which was developed and used in another substudy [48]. The outcome was defined by the following criteria: spontaneous onset of labour at 37 through 42 gestational weeks leading to spontaneous birth of an infant with a minimum Apgar score of 9 at 5 min combined with the absence of caesarean section, instrumental delivery, medical augmentation of labour, episiotomy, shoulder dystocia, third/fourth-degree perineal tearing, uterine rupture, retained placenta and postpartum bleeding >500 ml.…”