Maternal and newborn morbidity by birth facility among selected United States 2006 low-risk births




Objective


We sought to evaluate perinatal morbidity by delivery location (hospital, freestanding birth center, and home).


Study Design


Selected 2006 US birth certificate data were accessed online from the Centers for Disease Control and Prevention. Low-risk maternal and newborn outcomes were tabulated and compared by birth facility.


Results


A total of 745,690 deliveries were included, of which 733,143 (97.0%) occurred in hospital, 4661 (0.6%) at birth centers, and 7427 (0.9%) at home. Compared with hospital deliveries, home and birthing center deliveries were associated with more frequent prolonged and precipitous labors. Home births experienced more frequent 5-minute Apgar scores <7. In contrast, home and birthing center deliveries were associated with less frequent chorioamnionitis, fetal intolerance of labor, meconium staining, assisted ventilation, neonatal intensive care unit admission, and birthweight <2500 g.


Conclusion


Home births are associated with a number of less frequent adverse perinatal outcomes at the expense of more frequent abnormal labors and low 5-minute Apgar scores.


Almost 1 in 200 US women giving birth does so at home, accounting for approximately 25,000 deliveries annually. Two-thirds of these deliveries were attended by a physician or midwife, suggesting that home birth represented a conscious choice by the majority of these mothers. Home birth policy statements by several professional organizations are surprisingly discordant despite considering the same body of evidence, most of which comes from European studies.


The American College of Obstetricians and Gynecologists (ACOG) “strongly opposes home births,” citing a lack of scientific rigor in studies comparing the safety and outcomes of US hospital births to those occurring elsewhere. In support of home birth, the American College of Nurse Midwives notes that “high-quality controlled trials and descriptive studies have established that planned home births achieve excellent perinatal outcomes” while decreasing the use of potentially harmful medical interventions. Finally, the Association of Women’s Health, Obstetric, and Neonatal Nurses “supports a woman’s right to choose and have access to a full range of providers and settings for pregnancy, birth, and women’s health care.”


In the absence of professional consensus and adequate US data regarding the safety and outcomes of home birth, we sought to compare maternal and newborn morbidity by delivery location among women at low obstetric risk.


Materials and Methods


This investigation is a retrospective population-based cohort study using US 2006 birth data files at the state level, which were accessed online at the Centers for Disease Control and Prevention (CDC) National Center for Health Statistics ( www.cdc.gov/nchs/datawh/vitalstats/VitalStatsbirths.htm ). Demographics and maternal and newborn outcomes were selected from the 2003 revision of the US Standard Certificate of Live Birth, used by 19 states and representing 49% of all US births. These states were California, Delaware, Florida, Idaho, Kansas, Kentucky, Nebraska, New Hampshire, New York (excluding New York City), North Dakota, Ohio, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Vermont, Washington, and Wyoming.


To identify a low obstetrical risk population, we excluded multiple gestations, preterm deliveries <37 weeks, smokers, women with pregestational or gestational diabetes, chronic hypertension, hypertensive disorders of pregnancy, or prior cesarean. Demographics included maternal age, race, education, and timeliness of registering for prenatal care. Maternal morbidity measures in this low-risk population included chorioamnionitis (clinical diagnosis of chorioamnionitis during labor made by delivery attendant, usually includes >1 of the following: fever, uterine tenderness and/or irritability, leukocytosis, fetal tachycardia, any maternal temperature ≥38°C [100.4°F]), fetal intolerance of labor (in utero resuscitative measures, eg, any of the following: maternal position change, oxygen administration to the mother, intravenous fluids administered to the mother, amnioinfusion, support of maternal blood pressure, and administration of uterine relaxing agents; further fetal assessment includes any of the following: scalp pH, scalp stimulation, acoustic stimulation; operative delivery is operative intervention to shorten time to delivery of the fetus, eg, forceps, vacuum, or cesarean delivery), prolonged labor (labor that progresses slowly and lasts for ≥20 hours), precipitous labor (labor that progresses rapidly and lasts for <3 hours), and meconium staining (staining of the amniotic fluid caused by passage of fetal bowel contents during labor and/or at delivery that is more than enough to cause a greenish color change of an otherwise clear fluid). Newborn morbidity included assisted ventilation (infant given manual breaths for any duration with bag and mask or bag and endotracheal tube within the first several minutes from birth, excludes oxygen only and laryngoscopy for aspiration of meconium), assisted ventilation >6 hours (infant given mechanical ventilation [breathing assistance] by any method for >6 hours, includes conventional, high-frequency, and/or continuous positive pressure), birth injury (defined as present immediately following delivery or manifesting soon after delivery, includes any bony fracture or weakness or loss of sensation but excludes fractured clavicles and transient facial nerve palsy; soft tissue hemorrhage requiring evaluation and/or treatment, includes subgaleal [progressive extravasation within the scalp] hemorrhage, giant cephalohematoma, extensive truncal, facial, and/or extremity ecchymosis accompanied by evidence of anemia and/or hypovolemia and/or hypotension; solid organ hemorrhage, includes subcapsular hematoma of the liver, fractures of the spleen, or adrenal hematoma), neonatal intensive care unit (NICU) admission (admission into a facility or unit staffed and equipped to provide continuous mechanical ventilatory support for a newborn), seizures (seizure is any involuntary repetitive, convulsive movement or behavior; serious neurologic dysfunction is severe alteration of alertness, such as obtundation, stupor, or coma, ie, hypoxic-ischemic encephalopathy, excludes lethargy or hypotonia in the absence of other neurologic findings, excludes symptoms associated with central nervous system congenital anomalies), 5-minute Apgar score <7, and birthweight <2500 g.


Custom tables were generated using the online Vital Stats software (Victoria, Australia), comparing demographic characteristics and morbidity measures by delivery location (hospital, freestanding birthing center, or residence). Data were analyzed by the χ 2 test with Bonferroni correction, using P < .003 as significant. Descriptive statistics included odds ratios with 95% confidence intervals and rates expressed as occurrences per 1000 births. Outcomes recorded as “not stated” were tabulated but not included in denominators for statistical analysis.




Results


There were 4,265,555 births reported in 2006, of which 2,073,368 (48.6%) used the 2003 US birth certificate and 745,690 (17.5%) met inclusion criteria. Of these births, 733,143 (97.0%) occurred in hospitals, 4661 (0.6%) in birth centers, and 7427 (0.9%) at home. Physicians delivered 678,234 infants in hospital, 620 in freestanding birthing centers, and 295 at home. Certified nurse midwives attended 51,555 in-hospital births, 2067 freestanding birthing center deliveries, and 1786 home births. Other midwives delivered 634 infants in hospital, 1865 in freestanding birthing centers, and 3521 at home. The remaining birth attendants were categorized as “not stated” or “other” (n = 4801; 0.6%). Physicians or midwives attended 5602 of 7427 (75.4%) home births, suggesting that the majority of home deliveries were planned. Subject demographics are presented in Table 1 . Compared with women delivering in hospital, those delivering in freestanding birthing centers or at home were more often older, multiparous, and white, with less formal education and later registration for prenatal care. Maternal and newborn outcomes are presented in Table 2 . Outcomes were missing for 0.1–1.7% of births, depending on the measure. Compared with women delivering in hospitals, those giving birth in birth centers or at home had more frequent prolonged and precipitous labors. Home births were also associated with higher rates of low 5-minute Apgar scores. In contrast, home and birthing center deliveries were associated with less chorioamnionitis, fetal intolerance of labor, meconium staining, assisted ventilation, NICU admissions, and birthweight <2500 g. There were no differences in assisted ventilation >6 hours, neonatal seizures, or birth injury rates by delivery location.



TABLE 1

Maternal demographics by delivery location

























































































































































































































Hospital (n = 733,143) Freestanding birthing center (n = 4661) Residence (n = 7427)
Demographic n % n % n % P
Age, y < .0001
<20 87,177 11.9 184 3.9 168 2.3
20–29 401,807 54.1 2642 56.7 3749 50.5
30–39 230,546 31.4 1701 36.5 3122 42.0
≥40 13,613 1.9 134 2.9 388 5.2
Parity < .0001
Nulliparous 277,421 37.9 1154 24.7 1136 15.3
Parous 444,480 60.6 3476 76.6 6070 81.7
Race < .0001
White 600,885 81.9 4429 95.0 7014 94.4
Black 97,091 13.2 138 3.0 294 4.0
American Indian 4887 0.7 18 0.4 24 0.3 .
Asian/Pacific Islander 30,676 4.2 76 1.6 95 1.3
Education
≤12th grade 154,083 21.0 1740 37.3 2920 39.3
High school graduate 323,317 44.1 1334 28.6 2289 30.8
College degree 252,383 34.4 1578 33.9 2179 29.3
Initiation of prenatal care
First–third mo 496,240 67.7 2223 47.7 2899 39.0 < .0001
Fourth–sixth mo 159,293 21.7 1709 36.7 3092 40.4
Seventh–tenth mo 39,213 5.3 662 14.2 926 12.5
No prenatal care 14,411 2.0 24 0.5 359 4.8

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Jul 8, 2017 | Posted by in GYNECOLOGY | Comments Off on Maternal and newborn morbidity by birth facility among selected United States 2006 low-risk births

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