Outcomes for births booked under an independent midwife and births in NHS maternity units: matched comparison study

BMJ. 2009 Jun 11;338:b2060. doi: 10.1136/bmj.b2060.

Abstract

Objective: To compare clinical outcomes between women employing an independent midwife and comparable pregnant women using NHS services.

Design: Anonymised matched cohort analysis. Cases from the database of the Independent Midwives' Association (IMA) matched up to 1:5 with Scottish National Health Service (NHS) records for age, parity, year of birth, and socioeconomic status. Multivariable logistic regression models used to explore the relation between explanatory variables and outcomes; analyses controlled for potential confounding factors and adjusted for stratification.

Setting: UK databases 2002-5.

Participants: Anonymised records for 8676 women (7214 NHS; 1462 IMA).

Main outcome measures: Unassisted vertex delivery, live birth, perinatal death, onset of labour, gestation, use of analgesia, duration of labour, perineal trauma, Apgar scores, admission to neonatal intensive care, infant feeding.

Results: IMA cohort mothers were significantly more likely to achieve an unassisted vertex delivery than NHS cohort mothers (77.9% (1139) v 54.3% (3918); odds ratio 3.49, 95% confidence interval 2.99 to 4.07) but also significantly more likely to experience a stillbirth or a neonatal death (1.7% (25) v 0.6% (46); 5.91, 3.27 to 10.7). All odds ratios are adjusted for confounding factors. Exclusion of "high risk" cases from both cohorts showed a non-significant difference (0.5% (5) v 0.3% (18); 2.73, 0.87 to 8.55); the "low risk" IMA perinatal mortality rate is comparable with other studies of low risk births. Women in the IMA cohort had a higher incidence of pre-existing medical conditions (1.5% (22) v 1.0% (72) in the NHS cohort) and previous obstetric complications (21.0% (307) v 17.8% (1284)). The incidence of twin pregnancy was also higher (3.4% (50) v 3.1% (224)). In the IMA cohort, 66.0% of mothers (965/1462) had home births, compared with only 0.4% of NHS cohort mothers (27/7214). Spontaneous onset of labour was more common in the IMA group (96.6% (1405) v 74.5% (5365); 10.43, 7.74 to 14.0), and fewer mothers used pharmacological analgesia (40.2% (588) v 60.6% (4370); 0.42, 0.38 to 0.47). Mothers in the IMA cohort were much more likely to breast feed (88.0% (1286) v 64.0% (2759); 3.46, 2.84 to 4.20). Prematurity (4.3% (63) v 6.9% (498); 0.49, 0.35 to 0.69), low birth weight (4.0% (60) v 7.1%) (523); 0.93, 0.62 to 1.38), and rate of admission to neonatal intensive care (4.4% (65) v 9.3% (667); 0.43, 0.32 to 0.59) were all higher in the NHS dataset.

Conclusions: Healthcare policy tries to direct patient choice towards clinically appropriate and practicable options; nevertheless, pregnant women are free to make decisions about birth preferences, including place of delivery and staff in attendance. While clinical outcomes across a range of variables were significantly better for women accessing an independent midwife, the significantly higher perinatal mortality rates for high risk cases in this group indicate an urgent need for a review of these cases. The significantly higher prematurity and admission rates to intensive care in the NHS cohort also indicate an urgent need for review.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Cohort Studies
  • Female
  • Home Childbirth / statistics & numerical data*
  • Hospitalization / statistics & numerical data*
  • Hospitals, Maternity / statistics & numerical data*
  • Humans
  • Intensive Care, Neonatal / statistics & numerical data
  • Midwifery / statistics & numerical data*
  • Pregnancy
  • Pregnancy Complications / epidemiology*
  • Pregnancy Outcome / epidemiology*
  • Scotland / epidemiology
  • State Medicine
  • Young Adult