An alternative model of maternity care for low-risk birth: Maternal and neonatal outcomes utilizing the midwifery-based birth center model.

OBJECTIVE: To assess key birth outcomes in an alternative maternity care model, midwifery-based birth center care. DATA SOURCES: The American Association of Birth Centers Perinatal Data Registry and birth certificate files, using national data collected from 2009 to 2019. STUDY DESIGN: This observational cohort study compared key clinical birth outcomes of women at low risk for perinatal complications, comparing those who received care in the midwifery-based birth center model versus hospital-based usual care. Linear regression analysis was used to assess key clinical outcomes in the midwifery-based group as compared with hospital-based usual care. The hospital-based group was selected using nearest neighbor matching, and the primary linear regressions were weighted using propensity score weights (PSWs). The key clinical outcomes considered were cesarean delivery, low birth weight, neonatal intensive care unit admission, breastfeeding, and neonatal death. We performed sensitivity analyses using inverse probability weights and entropy balancing weights. We also assessed the remaining role of omitted variable bias using a bounding methodology. DATA COLLECTION: Women aged 16-45 with low-risk pregnancies, defined as a singleton fetus and no record of hypertension or cesarean section, were included. The sample was selected for records that overlapped in each year and state. Counties were included if there were at least 50 midwifery-based birth center births and 300 total births. After matching, the sample size of the birth center cohort was 85,842 and the hospital-based cohort was 261,439. PRINCIPAL FINDINGS: Women receiving midwifery-based birth center care experienced lower rates of cesarean section (-12.2 percentage points, p < 0.001), low birth weight (-3.2 percentage points, p < 0.001), NICU admission (-5.5 percentage points, p < 0.001), neonatal death (-0.1 percentage points, p < 0.001), and higher rates of breastfeeding (9.3 percentage points, p < 0.001). CONCLUSIONS: This analysis supports midwifery-based birth center care as a high-quality model that delivers optimal outcomes for low-risk maternal/newborn dyads.

The birth center model of care: Staffing, business characteristics, and core clinical outcomes.

OBJECTIVES: Interest in expanding access to the birth center model is growing. The purpose of this research is to describe birth center staffing models and business characteristics and explore relationships to perinatal outcomes. METHODS: This descriptive analysis includes a convenience sample of all 84 birth center sites that participated in the AABC Site Survey and AABC Perinatal Data Registry between 2012 and 2020. Selected independent variables include staffing model (CNM/CM or CPM/LM), legal entity status, birth volume/year, and hours of midwifery call/week. Perinatal outcomes include rates of induction of labor, cesarean birth, exclusive breastfeeding, birthweight in pounds, low APGAR scores, and neonatal intensive care admission. RESULTS: The birth center model of care is demonstrated to be safe and effective, across a variety of staffing and business models. Outcomes for both CNM/CM and CPM/LM models of care exceed national benchmarks for perinatal quality with low induction, cesarean, NICU admission, and high rates of breastfeeding. Within the sample of medically low-risk multiparas, variations in clinical outcomes were correlated with business characteristics of the birth center, specifically annual birth volume. Increased induction of labor and cesarean birth, with decreased success breastfeeding, were present within practices characterized as high volume (>200 births/year). The research demonstrates decreased access to the birth center model of care for Black and Hispanic populations. CONCLUSIONS FOR PRACTICE: Between 2012 and 2020, 84 birth centers across the United States engaged in 90,580 episodes of perinatal care. Continued policy development is necessary to provide risk-appropriate care for populations of healthy, medically low-risk consumers.

The importance of nutrition in pregnancy and lactation: lifelong consequences.

Most women in the United States do not meet the recommendations for healthful nutrition and weight before and during pregnancy. Women and providers often ask what a healthy diet for a pregnant woman should look like. The message should be "eat better, not more." This can be achieved by basing diet on a variety of nutrient-dense, whole foods, including fruits, vegetables, legumes, whole grains, healthy fats with omega-3 fatty acids that include nuts and seeds, and fish, in place of poorer quality highly processed foods. Such a diet embodies nutritional density and is less likely to be accompanied by excessive energy intake than the standard American diet consisting of increased intakes of processed foods, fatty red meat, and sweetened foods and beverages. Women who report "prudent" or "health-conscious" eating patterns before and/or during pregnancy may have fewer pregnancy complications and adverse child health outcomes. Comprehensive nutritional supplementation (multiple micronutrients plus balanced protein energy) among women with inadequate nutrition has been associated with improved birth outcomes, including decreased rates of low birthweight. A diet that severely restricts any macronutrient class should be avoided, specifically the ketogenic diet that lacks carbohydrates, the Paleo diet because of dairy restriction, and any diet characterized by excess saturated fats. User-friendly tools to facilitate a quick evaluation of dietary patterns with clear guidance on how to address dietary inadequacies and embedded support from trained healthcare providers are urgently needed. Recent evidence has shown that although excessive gestational weight gain predicts adverse perinatal outcomes among women with normal weight, the degree of prepregnancy obesity predicts adverse perinatal outcomes to a greater degree than gestational weight gain among women with obesity. Furthermore, low body mass index and insufficient gestational weight gain are associated with poor perinatal outcomes. Observational data have shown that first-trimester gain is the strongest predictor of adverse outcomes. Interventions beginning in early pregnancy or preconception are needed to prevent downstream complications for mothers and their children. For neonates, human milk provides personalized nutrition and is associated with short- and long-term health benefits for infants and mothers. Eating a healthy diet is a way for lactating mothers to support optimal health for themselves and their infants.

Effect of weight and adiposity at conception and wide variations in gestational dietary intake on pregnancy outcome and early postnatal performance in young adolescent sheep.

Nutritional backgrounds prior to pregnancy may interact with subsequent gestational intake to influence pregnancy outcome, particularly in young, growing adolescents. To investigate this interaction, singleton pregnancies were established in two groups of adolescent sheep of identical age but different initial weight and adiposity score, classified as good (G) and poor (P) body mass index (BMI). Thereafter, ewes were offered either an optimal control (C) intake to maintain adiposity throughout pregnancy, undernourished (UN) to maintain weight at conception but deplete maternal body reserves, or overnourished (ON) to promote rapid maternal growth and adiposity, resulting in a 2 x 3 factorial design. Gestation length was independent of BMI and reduced in ON dams. Average placental and lamb birth weights were influenced by initial BMI (G > P) and gestational intake (C > UN > ON), with the highest incidence of growth restriction in ON groups. Metabolic challenges at two thirds of gestation revealed enhanced insulin insensitivity in ON dams (higher glucose postinsulin challenge and higher insulin postglucose challenge), but nevertheless fetal growth was constrained. Initial colostrum yield, total IgG, and nutrient supply were reduced in ON groups, but these low-birth-weight lambs exhibited rapid catch-up growth to weaning. Thus, both maternal BMI at conception and gestational intake have a profound influence on pregnancy outcome in young, putatively growing adolescent sheep and may have implications for the nutritional management of pregnant adolescent humans.

Expression of energy balance regulatory genes in the developing ovine fetal hypothalamus at midgestation and the influence of hyperglycemia.

Evidence suggests that the prenatal nutritional environment influences the risk of developing obesity, a major health problem worldwide. It is hypothesized that fetal nutrition influences the developing neuroendocrine hypothalamus, the integrative control center for postnatal energy balance regulation. The present aim was to determine whether relevant hypothalamic genes are expressed in midgestation and whether they are nutritionally (glucose) sensitive at this time. Hypothalami from a cohort of 81-day singleton sheep fetuses, with varying glycemia by virtue of maternal dietary and/or growth hormone treatment, were subject to in situ hybridization analysis for primary orexigenic, anorexigenic, and related receptor genes (term = 147 days, n = 24). Neuropeptide Y, agouti-related peptide, proopiomelanocortin (POMC), cocaine- and amphetamine-regulated transcript (CART), and insulin receptor mRNAs were all localized in the hypothalamic arcuate nucleus (ARC) of all fetuses, whereas leptin receptor mRNA was expressed more abundantly in the ventromedial hypothalamic nucleus. ARC expression levels of POMC and CART genes, but none of the other genes, were positively correlated with fetal plasma glucose concentrations. Therefore, key central components of adult energy balance regulation were already present as early as midgestation (equivalent to 22 wk in humans), and two anorexigenic components were upregulated by elevated glycemia. Such changes provide a potential mechanism for the prenatal origins of postnatal energy balance dysregulation and obesity.

Effect of diet composition on pregnancy outcome in overnourished rapidly growing adolescent sheep.

When pregnant adolescent sheep are overnourished to promote maternal growth during pregnancy, growth of the placenta is impaired and results in the premature delivery of low birth weight lambs relative to control-fed adolescents of equivalent age. These effects have been achieved by feeding two levels of the same complete diet. The present study evaluated the role of protein in pregnancy outcome in our adolescent sheep paradigm. Adolescent ewes were implanted with single embryos on day 4 post-oestrus. Thereafter ewes were offered ad libitum an isoenergetic diet (11.4 MJ metabolisable energy/kg DM) containing either 12% (basic, B) or 17% (extra, E) crude protein. At day 75 of gestation, half the pregnant ewes on each protein level were switched to yield four groups, BB, EE, BE and EB protein. A further optimally nourished control group received a moderate quantity of a ration (14% crude protein) designed to provide 100% of the estimated energy and protein requirement of the adolescent sheep according to stage of pregnancy. Pregnancy outcome was determined at term. Feed intakes were independent of protein level in the four groups of ewes fed ad libitum and were higher (P<0.001) than in the control group throughout. Maternal plasma urea concentrations reflected the current crude protein content of the diet offered and were elevated in the 17% compared with 12% protein groups (P<0.001). Within groups fed ad libitum, maternal plasma insulin, glucose, NEFA and homocysteine concentrations were largely independent of protein level. Gestation length, placental weight, lamb birth weight and initial colostrum yield were reduced (P<0.05) in all groups fed ad libitum relative to the optimally nourished control group. Similarly, total colostrum IgG, butterfat, lactose and crude protein content at parturition were attenuated in the ad libitum compared with the control groups. However, within ad libitum groups pregnancy outcome parameters were largely unaffected by level or timing of exposure to high protein intakes. The data imply that it is high-energy intakes that are the primary cause of impaired placental development and adverse pregnancy outcome in rapidly growing adolescent sheep.

The effect of overnourishing singleton-bearing adult ewes on nutrient partitioning to the gravid uterus.

Overnourishing the singleton-bearing adolescent sheep throughout pregnancy promotes maternal tissue synthesis at the expense of the nutrient requirements of the gravid uterus. Consequently, the growth of the placenta is impaired and results in the premature delivery of low-birth-weight lambs relative to moderately fed adolescents of equivalent age. To establish if this phenomenon is unique to the growing animal, singleton pregnancies to a single sire were established by embryo transfer into primiparous adult ewes who had attained the normal mature body size for their genotype. Thereafter ewes were offered a maintenance or a high level of a complete diet throughout gestation. High maternal intakes resulted in elevated maternal insulin, no significant change in growth hormone or glucose, and attenuated progesterone and NEFA concentrations. Live weight gain during the first 93 d of gestation was 48 and 244 g/d, and adiposity score at term was 2.4 and 3.7 in the maintenance and high groups, respectively (P<0.001). In spite of achieving levels of adiposity similar to overnourished adolescents, placental (477 (sem 30) v. 518 (sem 41) g) and fetal (5190 (sem 320) v. 5420 (sem 250) g) weights were equivalent in maintenance and high groups. Gestation length was shorter (P<0.01) and colostrum yield at parturition lower (P<0.05) in high v. maintenance dams. Thus, adult sheep appear to be relatively insensitive to the oversupply of nutrients during pregnancy and have the ability to meet the nutrient requirements for normal conceptus growth in spite of their increased adiposity.

Maternal growth hormone treatment from day 35 to 80 of gestation alters nutrient partitioning in favor of uteroplacental growth in the overnourished adolescent sheep.

Overnourishing the pregnant adolescent ewe promotes maternal tissue synthesis at the expense of placental growth and leads to a major reduction in lamb birth weight at term. Growth hormone (GH) secretion is attenuated in these overnourished dams and the maternal somatotrophic axis may play a key role in coordinating nutrient usage in the pregnant adolescent. Thus we investigated whether increasing maternal GH during the period of rapid placental proliferation alters nutrient partitioning between the maternal, placental, and fetal tissues as assessed at Day 81 of gestation. Adolescent recipient ewes were implanted with singleton embryos, derived from superovulated dams and a single sire on Day 4 postestrus. Thereafter, the ewes were offered either a high (H) or moderate intake (M) of the same complete diet. From Day 35 to 80 of gestation, ewes were either injected twice daily (s.c. at 0800 and 1800 h) with recombinant bovine GH (bGH, 0.14 mg/kg live weight/day) or remained untreated (n = 8 ewes per group). Maternal concentrations of GH, insulin, insulin-like growth factor (IGF-1), glucose, and non-esterified fatty acids (NEFAs) were higher, and leptin secretion lower, in bGH-treated dams from both nutritional groups. Maternal body weight gain was higher in H versus M groups and was independent of bGH treatment. Treatment with bGH reduced relative perirenal and carcass fat deposition and increased carcass protein content in both H and M dams. Uteroplacental mass (uterus + placentomes + fetal membranes) averaged 1099, 1069, 1112, and 1754 g in M, H, M+GH, and H+GH groups. This significant increase in uteroplacental development in the H+GH group was associated with higher fetal kidney and liver weights and elevated fetal insulin, glucose, and lactate concentrations. Treatment with bGH also induced polyhydramnios in the H group. The transplacental glucose gradient was increased twofold in the H+GH group but placental GLUT- 1 and GLUT-3 expression was unaffected. In conclusion, administration of GH during the period of rapid placental proliferation alters endocrine status and thus nutrient partitioning in the overnourished adolescent dam in favor of uteroplacental and fetal growth. It remains to be established whether these effects are due wholly to alterations in maternal metabolism or if they also reflect an effect of bGH and/or the IGF system at the level of the uteroplacenta.