Search strategy

Computerized literature searches of MEDLINE and EMBASE were performed by a physician and medical librarian.

MEDLINE search results

The search strategy for the query for “all studies, regardless of methods, comparing intended/planned home births to intended/planned hospital births for maternal and newborn outcomes” was run in the MEDLINE database from 1950 through November week 1 2009 ( Figure 1 ). The following terms were used: explosion of the medical subject heading “Home Childbirth” (defined as childbirth taking place at home); explosion of the medical subject heading “Delivery, Obstetric” (defined as delivery of the fetus and placenta under the care of an obstetrician or a health worker; obstetric deliveries may involve physical, psychological, medical, or surgical interventions); explosion of the medical subject heading “Hospitalization” (defined as being in a hospital or being placed in a hospital; the confinement of a patient in a hospital); and explosion of the medical subject heading “Inpatients” (defined as persons admitted to health facilities that provide board and room, for the purpose of observation, care, diagnosis, or treatment). The terms “Hospitalization” or “Inpatients” or any mention of the word form “Hospital*” (designated with an asterisk as the wild card picking up any letters after the “l,” eg, “hospitals,” “hospitalized”) was then combined with the term “Delivery, Obstetric” to limit to a hospital birth. These results were then “anded” with the term “Home Childbirth” and by doing so indicated that the citation must include indexing for both terms; thus the discussion in the article would include both concepts. Limits to English language and human studies were then included. The final line of strategy was to take the retrieval and limit to any citations that would include the word forms for “outcome*” or “compar*” or “intend*” or “plan*” as a way to narrow the results to include the concepts of outcomes, comparisons, comparing, intended, or planned by using the asterisk as a wild card.

MEDLINE search strategy

Wax. Outcomes in planned home birth vs planned hospital births. Am J Obstet Gynecol 2010.

EMBASE search results

This strategy was done using EMBASE classic (1947 through present). Using the all subject words feature the term “Home Delivery” was searched. The term “Childbirth” was also searched and combined with any form of the word “Hospital?” with the ? indicating a wild card to pick up any forms of the word, such as “hospitals” and “hospitalization.”

The Cochrane Database of Systematic Reviews was also searched for relevant publications. Titles and abstracts of citations were reviewed for potential relevance and selected manuscripts were reviewed. References in these papers were manually reviewed and retrieved if potentially relevant.

Study selection criteria

Inclusion criteria were determined before the literature search was performed. Studies were included if performed in developed Western countries, published in English-language peer-reviewed literature, maternal and newborn outcomes were analyzed by planned delivery location, and data were presentable in a 2×2 table. Manuscripts were evaluated for quality using a published instrument. Outcome data were extracted by 2 physicians, with differences resolved by consensus. Outcomes for maternal intervention included epidural analgesia, electronic fetal heart rate monitoring, episiotomy, operative vaginal delivery (forceps or vacuum), and cesarean delivery. Maternal outcomes included mortality, morbidity measures of lacerations (≥3 degrees, vaginal, and perineal), infections (chorioamnionitis, endometritis, wound, and urinary), postpartum hemorrhage, retained placenta, and umbilical cord prolapse. Neonatal outcomes included 5-minute Apgar score <7, prematurity (<37 weeks’ gestation), low birthweight (<10% for gestational age or <2500 g), macrosomia (≥90% for gestational age or ≥4000 g), postdatism (≥42 weeks’ gestation), assisted ventilation requirement, perinatal death (stillbirth of at least 20 weeks or 500 g or death of liveborn within 28 days of birth), and neonatal death (death of a liveborn within 28 days of delivery). Perinatal and neonatal deaths were evaluated overall and for nonanomalous offspring. The study did not require institutional review board approval.

Statistical methods

Studies were assessed for homogeneity using the Breslow-Day test. When present, a fixed effects model was used; when absent, a random effects model was employed. Summary odds ratios (ORS) with 95% confidence intervals (CIS) were calculated for maternal and newborn outcomes, comparing planned home to planned hospital deliveries. Sensitivity analyses were conducted for studies employing matched planned home and hospital births, those primarily based upon pre-1990 data, lesser quality reports, and those not clearly specifying home birth attendants or in which home births were conducted by other than certified or certified nurse midwives. We used software (SAS, version 9.2; SAS Institute Inc, Cary, NC) for most data analysis. Random effects results were analyzed using an online metaanalysis calculator from the University of Pittsburgh ( http://www.pitt.edu/∼super1/lecture/lec1171/meta5.doc ).