Objective
To examine the occurrence of 5-minute Apgar scores of 0 and seizures or serious neurologic dysfunction for 4 groups by birth setting and birth attendant (hospital physician, hospital midwife, free-standing birth center midwife, and home midwife) in the United States from 2007-2010.
Methods
Data from the United States Centers for Disease Control’s National Center for Health Statistics birth certificate data files were used to assess deliveries by physicians and midwives in and out of the hospital for the 4-year period from 2007-2010 for singleton term births (≥37 weeks’ gestation) and ≥2500 g. Five-minute Apgar scores of 0 and neonatal seizures or serious neurologic dysfunction were analyzed for 4 groups by birth setting and birth attendant (hospital physician, hospital midwife, freestanding birth center midwife, and home midwife).
Results
Home births (relative risk [RR], 10.55) and births in free-standing birth centers (RR, 3.56) attended by midwives had a significantly higher risk of a 5-minute Apgar score of 0 ( P < .0001) than hospital births attended by physicians or midwives. Home births (RR, 3.80) and births in freestanding birth centers attended by midwives (RR, 1.88) had a significantly higher risk of neonatal seizures or serious neurologic dysfunction ( P < .0001) than hospital births attended by physicians or midwives.
Conclusion
The increased risk of 5-minute Apgar score of 0 and seizures or serious neurologic dysfunction of out-of-hospital births should be disclosed by obstetric practitioners to women who express an interest in out-of-hospital birth. Physicians should address patients’ motivations for out-of-hospital delivery by continuously improving safe and compassionate care of pregnant, fetal, and neonatal patients in the hospital setting.
Home births have increased in the United States in the last decade, allthough home births in the Netherlands, the country with the greatest experience with home births, have decreased. The 2011 American College of Obstetricians and Gynecologists’ Committee Opinion, “Planned Home Birth,” provides a useful review of the literature. The Cochrane Collaboration has published 2 reviews, one of clinical trials comparing planned hospital birth with planned home birth and another of trials comparing institutional and alternative birth settings. The safety of out-of-hospital birth remains controversial. The purpose of this study was to examine the occurrence of 5-minute Apgar scores of zero and seizures or serious neurologic dysfunction for 4 groups by birth setting and birth attendant (hospital physician, hospital midwife, freestanding birth center midwife, and home midwife) in the United States from 2007-2010.
Materials and Methods
Data were obtained from the National Center for Health Statistics (NCHS) of the US Centers for Disease Control (CDC) birth certificate data for 2007-2010, the most recent data available. The CDC files contain detailed information on each of the approximately 4 million births in the United States each year. Data on patient characteristics include setting and method of delivery as well as birth attendant as reported on birth certificates filed each year with the states of the United States and compiled by NCHS. These data are publicly accessible on the internet ( http://205.207.175.93/vitalstats/ReportFolders/ReportFolders.aspx ), where detailed tables can be created and downloaded for further evaluation.
The data that we report in this study are for the 2007-2010 period. We excluded preterm births (<37 weeks), infants weighing under 2500 g, and multiple gestations. This study therefore includes only singleton term births (deliveries ≥37 weeks) and infants weighing ≥2500 g.
Data on patients’ characteristics included parity, race and ethnicity, maternal age, and clinical factors including neonatal weight and weeks of gestation. We included patients in the 4 CDC categories that are described by birth setting and birth attendant: hospital-based physician; hospital-based midwife; freestanding birth center midwife; and home-based midwife.
Missing data were excluded for each parameter before percentages were computed. Differences noted as higher or lower were statistically significant at the P < .05 level.
Apgar scores are well reported on birth certificates. We included outcome data on 5-minute Apgar scores of 0, the clinical and prognostic utility of which is well established. We also included outcome data on neonatal seizures or serious neurologic dysfunction, the category used by the CDC. Since the introduction of the 2003 revised US Standard Certificate of Live Birth, outcome data such as seizures or serious neurologic dysfunction have been documented in 21 states in 2007, 27 states in 2008 and 2009, and 35 states in 2010. We calculated the risk ratios for seizures or serious neurologic dysfunction only for those states that had these data on their birth certificates, which included about 56% of all US births. Five-minute Apgar scores of 0 and data on seizure or serious neurologic dysfunction were placed into the same 4 groups by birth place and attendant. Five-minute Apgar scores of 0 and seizures or serious neurologic dysfunction are reported, as well as by parity (0, ≥1).
Bivariable analyses were conducted to determine whether characteristics of mothers and infants differed by the 4 groups. Hospital births attended by physicians served as the reference group in this analysis. For characteristics that had multiple levels (eg, age and race), a reference group was selected (<25-years-old for age and non-Hispanic white for race). All levels of the characteristic were individually compared with the reference group. χ 2 statistics were calculated for each bivariable analysis. Risk ratios and 95% confidence intervals (CIs) were calculated for each outcome in the 4 groups. Risks of the other 3 groups were individually compared with risks for hospital births attended by physicians. To account for confounding by parity, stratified analyses were conducted for parity = 0 and parity >0 for 5-minute Apgar scores of zero and seizures or serious neurologic dysfunction. In addition, stratum-specific estimates were calculated for maternal age <35-years-old, maternal age ≥35-year-old, gestational age 37-40 weeks, and gestational age ≥41 weeks for 5-minute Apgar scores of zero. All statistical analyses were conducted in OpenEpi (Open Source Epidemiologic Statistics for Public Health, Atlanta, GA).
Because nonidentifiable data from a publicly available dataset were used, our study was not considered human subjects research and did not require review by the institutional review board of Weill Medical College of Cornell University.
Results
From 2007 to 2010, there were a total of 16,693,978 births in the United States. Our study population consisted of 13,891,274 singleton deliveries, ≥37 weeks, with a birthweight ≥2500 g who were delivered in the hospital, a birthing center, or at home by either a physician or a midwife. In our study population, 5-minute Apgar scores were available for 98.8% of all states and for neonatal seizures or serious neurologic dysfunction in 97.5% of those states that had collected presence or absence of neonatal seizures or serious neurologic dysfunction in their birth certificates.
Table 1 shows patient characteristics and the distribution of the 4 groups of settings and birth attendants of our study population. There were a total of 13,891,274 births by physicians or midwives in the hospital, a freestanding birthing center, or at home between 2007 and 2010. The majority of term singleton births (91.16%; n = 12,663,051) were physician hospital births; midwife hospital births constituted 8.05% of birth (n = 1,118,678), and 0.49% (n = 67,429) were midwife home deliveries. Patients delivering at home attended by midwives were significantly more likely to be multiparous, non-Hispanic white, ≥30 years of age, delivering beyond 41 and 42 weeks, and having macrosomic infants over 4000 and 4500 g ( P < .0001).
| Characteristic | Hospital physician | Hospital midwife | Freestanding birth center midwife | Home midwife |
|---|---|---|---|---|
| TOTAL N = 13,891,274 | 12,663,051 (91.16) | 1,118,578 (8.05) | 42,216 (0.30) | 67,429 (0.49) |
| Para = 0 | n = 12,615,994 | n = 1,115,794 | n = 42,000 | n = 60,296 |
| Yes | 5,155,779 (40.9) | 44,0642 (39.5) | 15,228 (36.3) | 14,801 (24.5) |
| No | 7,460,215 (59.1) | 675,152 (60.5) | 26,772 (63.7) | 45,495 ( 75.4) |
| Ethnicity | n = 12,576,465 | n = 1,111,003 | n = 41,992 | n = 66,314 |
| Non-Hispanic white | 6,894,312 (54.8) | 585,553 (52.7) | 34,270 (81.6) | 60,017 (90.45) |
| Non-Hispanic black | 1,719,347 (13.7) | 145,442 (13.1) | 1865 (4.4) | 1314 (1.98) |
| Hispanic | 3,100,313 (24.7) | 301,223 (27.1) | 4759 (11.3) | 3533 (5.3) |
| Non-Hispanic other | 862,493 (6.9) | 78,785 (7.1) | 1098 (2.6) | 1490 (2.2) |
| Mother’s age | n = 12,553,246 | n = 1,118,578 | n = 42,216 | n = 67,429 |
| <25 y | 4,307,508 (34.3) | 449,318 (40.2) | 9338 (22.1) | 10,336 (15.3) |
| 25-29 y | 3,505,877 (27.9) | 325,607 (29.1) | 14,432 (34.2) | 20,899 (31.0) |
| 30-34 y | 2,957,460 (23.6) | 228,962 (20.5) | 12,119 (28.7) | 21,331 (31.6) |
| ≥35 y | 1,782,401 (14.2) | 114,691 (10.3) | 6327 (15.0) | 14,863 (22.0) |
| Post EDD | n = 12,701,519 | n = 1,118,936 | n = 42,229 | n = 67,504 |
| ≥41 wk | 1,982,383 (15.61) | 227,607 (20.34) | 11,184 (26.48) | 19,286 (28.57) |
| ≥42 wk | 798,882 (6.29) | 85,375 (7.63) | 3711 (8.79) | 6449 (9.55) |
| Macrosomia | n = 12,663,051 | n = 1,118,578 | n = 312,586 | n = 61,684 |
| ≥4000 g | 1,104,459 (8.72) | 98,644 (8.82) | 29,899 (9.57) | 12,831 (20.80) |
| ≥4500 g | 148,509 (1.17) | 11,114 (0.99) | 3699 (1.18) | 2538 (4.11) |
Table 2 shows the outcomes and relative risks (RRs) by the 4 groups of settings and attendants for 5-minute Apgar scores of 0, by parity. The RR of a 5-minute Apgar score of 0 for midwife home deliveries was 10.55 (95% CI, 8.62–12.93). The RR of a 5-minute Apgar score of 0 for midwife home deliveries further increased to 14.24 (95% CI, 10.16–19.96) for nulliparous patients. The RR for free-standing birth center midwife deliveries was less than home deliveries (3.56 vs 10.55) but it was increased relative to hospital deliveries by physicians or midwives. Within the hospital, midwife-attended deliveries had a lower RR (0.55; 95% CI, 0.45–0.68) compared with physicians.
| Outcome/Birth setting | n/Total (per 1000) | RR (95% CI) |
|---|---|---|
| 5-minute Apgar 0 (all) | ||
| Hospital MD | 1,943/12,615,994 (0.16) | 1.00 |
| Hospital midwife | 95/1,115,794 (0.09) | 0.55 (0.45–0.68) |
| Freestanding BC midwife | 23/42,000 (0.55) | 3.56 (2.36–5.36) |
| Home midwife | 98/60,296 (1.63) | 10.55 (8.62–12.93) |
| 5-minute Apgar 0 ( P = 0) | ||
| Hospital MD | 856/5,155,779 (0.17) | 1.00 |
| Hospital midwife | 37/440,642 (0.84) | 0.51 (0.36–0.70) |
| Freestanding BC midwife | 11/15,226 (7.22) | 4.35 (2.40–7.89) |
| Home midwife | 35/14,801 (2.36) | 14.25 (10.16–19.96) |
| 5-minute Apgar 0 ( P > 0) | ||
| Hospital MD | 1087/7,460,215 (0.15) | 1.00 |
| Hospital midwife | 58/675,152 (0.09) | 0.59 (0.45–0.77) |
| Freestanding BC midwife | 12/26,772 (0.45) | 3.08 (1.74–5.43) |
| Home midwife | 63/45,495 (1.35) | 9.5 (7.37–12.25) |
When we analyzed 5-minute Apgar scores of 0 for women <35 years of age, we found that the RR for midwife home deliveries was 8.76 (95% CI, 6.85–11.21) and for freestanding birth center midwife deliveries the RR was 4.28 (95% CI, 2.81–6.52). The RR for women ≥ 35 years of age for midwife home deliveries was 15.86 (95% CI, 10.97–22.92). When we analyzed 5-minute Apgar scores of 0 for women ≥41 weeks’ gestation we found that the RR for midwife deliveries was 6.5 (96% CI, 4.09–10.33) and 11.7 (95% CI, 9.33–14.68) for deliveries between 37-40 weeks.
Table 3 shows the outcomes by the 4 groups of settings and attendants for seizures or serious neurologic dysfunction and by parity. The RR of seizures or serious neurologic dysfunction for midwife home deliveries was 3.80 (95% CI, 2.80–5.16), and the RR of seizures or serious neurologic dysfunction for midwife home deliveries further increased to 6.28 (95% CI, 4.08–9.67) for nulliparous patients. Freestanding birthing centers midwife deliveries showed an increased risk of 1.88 (95% CI, 1.11–3.17) for seizures or serious neurologic dysfunction and an increased risk of 2.77 (95% CI, 1.48–5.15) for seizures or serious neurologic dysfunction for nulliparous patients. Within the hospital, midwife-attended deliveries had a lower RR compared with physicians (0.74; 95% CI, 0.62–0.89).
| Variable | N/Total (per 1000) | RR (95% CI) |
|---|---|---|
| Seizures (All) | ||
| Hospital MD | 1823/8,102,337 (0.22) | 1.00 |
| Hospital midwife | 121/727,395 (0.17) | 0.74 (0.62–0.89) |
| Freestanding BC midwife | 14/33,188 (0.42) | 1.88 (1.11–3.17) |
| Home midwife | 42/49,091 (0.86) | 3.8 (2.80–5.16) |
| Seizures ( P = 0) | ||
| Hospital MD | 981/3,297,301 (0.30) | 1.00 |
| Hospital midwife | 77/286,920 (0.27) | 0.90 (0.72–1.14) |
| Freestanding BC midwife | 10/12,155 (0.83) | 2.77 (1.48–5.15) |
| Home midwife | 21/11,239 (1.87) | 6.28 (4.08–9.67) |
| Seizures ( P > 0) | ||
| Hospital MD | 842/4,805,036 (0.18) | 1.00 |
| Hospital midwife | 44/440,475 (0.10) | 0.57 (0.42–0.77) |
| Freestanding BC midwife | 4/21,073 (0.19) | 1.08 (0.41–2.89) |
| Home midwife | 21/37,853 (0.55) | 3.17 (2.05–4.88) |
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