Pre-pregnancy weight and the risk of stillbirth and neonatal death

OBJECTIVE: To evaluate the association between maternal pre-pregnancy body mass index (BMI) and the risk of stillbirth and neonatal death and to study the causes of death among the children. DESIGN: Cohort study of pregnant women receiving routine antenatal care in Aarhus, Denmark. SETTING: Aarhus University Hospital, Denmark, 1989-1996. POPULATION: A total of 24,505 singleton pregnancies (112 stillbirths, 75 neonatal deaths) were included in the analyses. METHODS: Information on maternal pre-pregnancy weight, height, lifestyle factors and obstetric risk factors were obtained from self-administered questionnaires and hospital files. We classified the population according to pre-pregnancy BMI as underweight (BMI <18.5 kg/m(2)), normal weight (BMI 18.5-24.9 kg/m(2)), overweight (BMI 25-29.9 kg/m(2)) and obese (BMI 30.0 kg/m(2) or more). MAIN OUTCOME MEASURES: Stillbirth and neonatal death and causes of death. RESULTS: Maternal obesity was associated with a more than doubled risk of stillbirth (odds ratio = 2.8, 95% confidence interval [CI]: 1.5-5.3) and neonatal death (odds ratio = 2.6, 95% CI: 1.2-5.8) compared with women of normal weight. No statistically significantly increased risk of stillbirth or neonatal death was found among underweight or overweight women. Adjustment for maternal cigarette smoking, alcohol and caffeine intake, maternal age, height, parity, gender of the child, years of schooling, working status and cohabitation with partner did not change the conclusions, nor did exclusion of women with hypertensive disorders or diabetes mellitus. No single cause of death explained the higher mortality in children of obese women, but more stillbirths were caused by unexplained intrauterine death and fetoplacental dysfunction among obese women compared with normal weight women. CONCLUSION: Maternal obesity more than doubled the risk of stillbirth and neonatal death in our study. The present and other studies linking maternal obesity to an increased risk of severe adverse pregnancy outcomes emphasise the need for public interventions to prevent obesity in young women.     

Time since last birth and the risk of ovarian cancer

OBJECTIVES: While parity is a protective factor in ovarian cancer, the role of time factors of pregnancy and birth is still controversial. We considered therefore the role of birth timing in the risk in ovarian cancer from a large case-control study. METHODS: Cases were 971 women (age range 22-74 years, median age 54) with histologically confirmed, incident epithelial ovarian cancer, interviewed between 1983 and 1991 in a network of hospitals in Milan, Italy. Controls were 2758 women (age range 23-74 years, median age 52) admitted to the same hospitals where cases were identified for acute, nonneoplastic conditions. RESULTS: In comparison with nulliparous women, the multivariate odds ratios (OR) were 0.8 for women reporting one or two and 0.6 for those with three or more births. No clear association emerged between time since last birth and ovarian cancer. Compared to women who had last given birth since > or =20 years, a moderately increased risk of ovarian cancer was observed in the first 10 years after last birth, with an OR of 1.7 (95% confidence interval, CI 1.0-2.9). When we considered only multiparous women and included in the multivariate analysis allowance for age at first birth, the OR decreased to 1.2 (95% CI 0.6-2.4). No consistent pattern of trends was observed > or =10 years since last pregnancy. CONCLUSIONS: This study confirms the protective effect of parity on ovarian carcinogenesis, but shows no consistent pattern of risk across time since last birth.     

Maternal risk factors for cause-specific stillbirth and neonatal death

BACKGROUND: To study specific effects of four maternal risk factors: age, parity, educational level, smoking, for specific causes of stillbirth and neonatal death according to a previously described hierarchic classification. METHODS: The study is based on 9,785 stillbirths or neonatal deaths among infants born in Sweden, 1983-1995 (n=1,412,754) and identified with various Swedish health registers. Statistical analysis is performed using Mantel-Haenszel analysis. RESULTS: Some risk factors, known from the literature, were confirmed and could be quantified. In addition, high parity was shown to increase the risk for death associated with multiple births (OR=2.49, 95% CI 2.07-3.01) and low educational level seems to be protective for such death (OR=0.75, 95% CI 0.60-0.93). If the infant is SGA, the risk for death is higher at high than at low parity (1.70, 95% CI 1.19-2.43, and 1.0, 95% CI 1.06-1.15, respectively). Maternal smoking seems to aggravate the placental abruption because the death risk in the presence of abruption increases when the mother smoked (OR = 1.74, 95% CI 45-2.08). CONCLUSIONS: The study shows that the groups of the classification system used (NICE) differ in their association with known risk factors for stillbirth and neonatal deaths and an analysis based on specific causes of death can therefore unravel risk factors hidden when total mortality is used. The computerized method of classification and the cause-of-death classification developed by us is clearly useful for such analyses which requires large materials.     

Prenatal risk factors for intraventricular hemorrhage, neonatal death and impaired psychomotor development in very low birth weight infants

AIM: The aim of this study was to determine the relationship between preterm risk factors and neonatal death, cerebral hemorrhage and psychomotor development in very low birth weight infants. METHODS: A retrospective analysis based on a multivariate logistic regression model was conducted on 253 VLBW infants. Cerebral hemorrhage was assessed by cerebral ultrasound screening within 24 hours of life, psychomotor development by Bailey Psychomotor and Development Index test. RESULTS: Pre-eclampsia and elective cesarean section (CS) are statistically protective factors in the prevention of cerebral hemorrhage; gestational age is a protective factor for neonatal death; whereas, multiple pregnancy, symmetrically small for gestational-age infants, asphyxia at birth, altered cardiotocography, and cerebral hemorrhage are risk factors for neonatal death; emergency CS and gestational age are protective factors for problems in psychomotor development. The number of fetuses and cerebral hemorrhage are risk factors for impaired psychomotor development at 2 years of age. CONCLUSION: The great number of obstetrical variables related to neonatal outcome makes it difficult to identify the really important steps, in obstetric management, to prevent long term sequelae. The main risk factors related to psychomotor development still remain gestational age and multiple pregnancy.     

Obstetric risk factors for poor neonatal adaptation at birth

Purpose: To identify obstetric risk factors of delivering a neonate with poor neonatal adaptation at birth.

Material and methods: Nested case–control study. Poor neonatal adaptation was defined for presence of at least: umbilical cord artery pH <7.10, base deficit ≥12?mmol/L, Apgar score at 1′ ≤5. Controls were selected from the same population and matched with cases. The association between clinical parameters and poor neonatal adaptation was analyzed by logistic regression.

Results: One hundred and thirty three women (2.1% of all live births) with a neonate presenting a poor neonatal adaptation were matched with 133 subsequent controls. Significant contributions for the prediction of poor neonatal adaptation were provided by maternal age ≥35 years (p?≤?.001, odds ratio (OR) 3.9 [95%CI: 2.3–6.8]), nulliparity (p?≤?.001, OR 3.3 [95%CI: 1.8–6]), complications during pregnancy (p?=?.032, OR 2.2 [95%CI: 1.1–4.4]), gestational age at delivery <37 weeks (p?=?.008, OR 5.2 [95%CI: 1.5–17.8]) and cardiotocography category II or III (p?≤?.001, OR 36.3 [95%CI: 16.5–80.1]). The receiver operative characteristic curve was 0.91 [95%CI: 0.87–0.95], and detection rates 82.7% and 89.5% at 10% and 20% of false positive rates, respectively.

Conclusions: Several obstetric risk factors before and during labor can identify a subgroup of newborns at higher risk of a poor neonatal adaptation at birth.     

Sociodemographic factors associated with weekend birth and increased risk of neonatal mortality

OBJECTIVE: To learn whether weekend risk of neonatal mortality is related to selected sociodemographic factors. DESIGN: A retrospective cohort design. Logistic regression was used to obtain odds ratios, and analysis of variance and chi-square to identify differences in values and incidence of key variables. SAMPLES: The data were derived from matched Texas birth and infant death certificates from 1999 through 2001. MAIN OUTCOME MEASURES: A subset of deaths up to 28 days of life attributable to conditions originating in the perinatal period. These deaths were called neonatal mortality-p. RESULTS: Women who were White, married, had Medicaid assistance, and had private prenatal care were less likely to deliver on weekends. Odds of neonatal mortality-p increased 36.5% when a birth took place on the weekend. The weekend crude odds of neonatal mortality-p increased for all racial/ethnic groups, but the differences were not statistically significant. CONCLUSIONS: The likelihood of delivering on the weekend increases with certain sociodemographic factors. This fact is important because the risk of neonatal mortality is higher among weekend births.     

Factors differentiating postponed neonatal death from survival in low birth weight infants

Although survival of low birth weight infants during the neonatal period has improved, an increasing percentage of infants succumb after 28 days but before discharge from the nursery. In a retrospective study we compared 11 postponed neonatal deaths (PND) with survivors matched for birth weight, gestational age, gender, race, inborn or outborn status, and year of birth in an attempt to identify possible differentiating factors early in the clinical course. Evaluation of antenatal, intrauterine, and early nursery events could not differentiate the two groups. By day 14, however, significantly more PND required assisted ventilation because of poor respiratory effort and total parenteral nutrition because of poor gastrointestinal motility. Metabolic differences were noted at this time in the serum bilirubin, phosphorus, and chloride levels. At autopsy all infants had evidence of CNS injury, and moderate chronic lung disease, and in addition nine infants had bronchopneumonia. The major differences between the PNDs and survivors may primarily involve neurologic control of respiration and gastrointestinal motility. Early recognition of PND may have important medical, ethical, and financial implications for newborn intensive care.     

A case control study of risk factors and neonatal outcomes of preterm birth

Objective

The aim is to examine risk factors and neonatal outcomes of preterm birth and to provide basis in preventing preterm birth.

Preterm birth is associated with increased risk of maternal and neonatal infection.

Much information suggests that maternal reproductive tract infections, both recognized and unrecognized, account for an important and possibly preventable portion of preterm births. If such infections do mediate instances of preterm labor and premature rupture of the membranes (PROM), then associated risks of subsequent maternal and neonatal infections would be increased, even after controlling for confounding variables. To evaluate possible associations between preterm birth and maternal and neonatal infections, we conducted a retrospective study of 9642 births at the University of Colorado Health Sciences Center between July 1980 and June 1985. Clinical chorioamnionitis occurred more frequently among women delivering before term with intact membranes at the onset of labor (5.8% preterm versus 1.7% term) and among women with PROM (26.5% preterm versus 6.7% term). Among the women delivered by cesarean, the incidence of postpartum endometritis was higher in those with preterm PROM than in those with term rupture of membranes. The incidence of neonatal infection increased significantly as the gestational age of the neonates decreased (P less than .01). The rate of culture-proven neonatal infection was significantly higher following PROM (P less than .01) than after birth without PROM. Both neonatal infection and perinatal mortality were increased in association with chorioamnionitis in both preterm and term pregnancies. These consistent observations complement and support suggestions that reproductive tract infection plays a possibly preventable role in the pathogenesis of preterm birth.     

Maternal antibodies against cytomegalovirus in pregnancy and the risk of fetal death and low birth weight

BACKGROUND. The aim of this study was to assess the impact of maternal cytomegalovirus (CMV) antibody status in pregnancy on the risk of fetal death and of low birth weight. METHODS. The study of fetal death risk was a nested case-control study. Cases were all women within a cohort of 35,940 pregnant women in Norway 1992--94, who experienced fetal death after 16th week of gestation (n=281). Controls were 957 randomly selected women with live born children. Both groups were identified through linkage to the Norwegian Medical Birth Registry. The risk of low birth weight was studied in the live born children. RESULTS. Seventy-two percent (203/281) of the cases and 69% (662/957) of the controls had CMV immunoglobulin G (IgG) antibodies in the first trimester (P=0.3). 0.4% (1/281) of the cases and 0.7% (7/957) had CMV IgM antibodies in the first trimester (P=0.7). Among 322 initially CMV antibody-negative women, 11% (6/55) of the cases and 9% (24/267) of the controls had occurrence of CMV IgG and/or IgM antibodies (P=0.7) during pregnancy. Also, after control for maternal age, parity, and follow-up time, no association between CMV antibodies and fetal death was found. CMV antibody status was not associated with low birth weight. CONCLUSIONS. This study does not support a causal relation between CMV infection in pregnancy and fetal death or low birth weight.     

The influence of interpregnancy interval on the subsequent risk of stillbirth and early neonatal death

OBJECTIVE: To study whether interpregnancy interval is associated with increased risks of stillbirth and early neonatal death and whether this possible association is confounded by maternal characteristics and previous reproductive history. METHODS: In a Swedish nationwide study of 410,021 women's first and second singleton deliveries between 1983 and 1997, we investigated the influence of interpregnancy interval on the subsequent risks of stillbirth and early neonatal death. Odds ratios (ORs) with 95% confidence intervals (CIs) estimated using unconditional logistic regression were adjusted for maternal characteristics and previous pregnancy outcome categorized into stillbirth, early neonatal death, preterm, or small for gestational age delivery. RESULTS: Compared with interpregnancy intervals between 12 and 35 months, very short interpregnancy intervals (0-3 months) were, in the univariate analyses, associated with increased risks of stillbirth and early neonatal death (crude OR 1.9; 95% CI 1.3, 2.7; and 1.8; 1.2, 2.8, respectively). However, after adjusting for maternal characteristics and previous reproductive history, women with interpregnancy intervals of 0 to 3 months were not at increased risks of stillbirth (adjusted OR 1.3; 95% CI 0.8, 2.1) or early neonatal death (adjusted OR 0.9; 95% CI 0.5, 1.6). Women with interpregnancy intervals of 72 months and longer were at increased risk of stillbirth (adjusted OR 1.5; 95% CI 1.1, 2.1) and possibly early neonatal death (adjusted OR 1.3; 95% CI 0.9, 2.1). CONCLUSION: Short interpregnancy intervals appear not to be causally associated with increased risk of stillbirth and early neonatal death, whereas long interpregnancy intervals were associated with increased risk of stillbirth and possibly early neonatal death.     

Haplogroup-associated differences in neonatal death and incidence of low birth weight at elevation: a preliminary assessment

OBJECTIVE: We sought to assess reproductive fitness differences between mitochondrial deoxyribonucleic acid haplogroups at high altitude. STUDY DESIGN: This study considers differences in outcomes of conception, birth weight, and neonatal mortality rates for 62 women classified according to haplogroups (B or non-B). RESULTS: The number of low-weight births (<2500 g) for the non-B group was significant (P =.019). Mothers in the non-B group reported more spontaneous abortions (P =.171) and stillbirths (P =.301). The difference in conceptions per woman between groups was significant (P =.036). However, no difference in infants alive at 1 month of age was evident. Neonatal death was significant (P =.017). The odds of an unsuccessful outcome among mothers in the B group was compared with mothers in the non-B group and was significant (P =.029). The chance of an adverse outcome, that is, fetal or infant death before 1 month, for mothers in the B group was between 11.1% and 88.7% lower than for mothers in the non-B group. CONCLUSIONS: The neonatal mortality rate for the non-B group was significantly elevated relative to the B group. The molecular basis for these observations is not clear.     

Review of 1600 water births. Does water birth increase the risk of neonatal infection?

OBJECTIVES: We reviewed 1600 water births at a single institution over an 8-year period. METHODS: We compared 737 primiparae deliveries in water with 407 primiparae deliveries in bed, and 142 primiparae on the delivery stool. We also evaluated the duration of labor, perineal trauma, arterial cord blood pH, postpartum maternal hemoglobin levels, and rates of neonatal infection. In 250 water deliveries we performed bacterial cultures of water samples obtained from the bath after filling and after delivery. RESULTS: The duration of the first stage of labor was significantly shorter with a water birth than with a land delivery (380 vs. 468 minutes, P<0.01). The episiotomy rate in all water births was lower with a water birth than with a delivery in bed or a delivery on the birthing stool (0.38%, 23%, and 8.4%, respectively). The rate of perineal tears was similar (23%, respectively). There were no differences in the duration of the second stage (34 vs. 37 minutes), arterial cord blood pH, or postpartum maternal hemoglobin levels. No woman using the water birth method required analgesics. The rate of neonatal infection was also not increased with a water birth (1.22% vs. 2.64%, respectively). CONCLUSION: Water birth appears to be associated with a significantly shorter first stage of labor, lower episiotomy rate and reduced analgesic requirements when compared with other delivery positions. If women are selected appropriately and hygiene rules are respected, water birth appears to be safe for both the mother and neonate.     

Risk factors and neonatal/infant mortality risk of small-for-gestational-age and preterm birth in rural Nepal

Objective: Our study seeks to elucidate risk factors for and mortality consequences of small-for-gestational-age (SGA) and preterm birth in rural Nepal. In contrast with previous literature, we distinguish the epidemiology of SGA and preterm birth from each other.

Methods: We analyzed data from a maternal micronutrient supplementation trial in rural Nepal (n?=?4130). We estimated adjusted risk ratios (aRR) for risk factors of SGA and preterm birth, and aRRs for the associations between SGA/preterm birth and neonatal/infant mortality. We used mutually exclusive categories of term-appropriate-for-gestational-age (AGA), term-SGA, preterm-AGA, and preterm-SGA (with term-AGA as reference) in our analyses.

Results: Stunted (<145?cm) and wasted (<18.5?kg/m²) women both had increased risk of having term-SGA (aRR 1.36, 95% CI: 1.14-1.61, aRR 1.22, 95% CI: 1.09–1.36 respectively) and preterm-SGA (aRR 2.48, 95% CI: 1.29–4.74, aRR 1.99, 95% CI: 1.33–2.97 respectively), but not preterm-AGA births. Similar results were found for low maternal weight gain per gestational week. Those born preterm-SGA generally experienced the highest neonatal and infant mortality risk, although term-SGA and preterm-AGA newborns also had statistically significantly high mortality risks compared to term-AGA babies.

Conclusions: SGA and preterm birth have distinct risk factors and mortality patterns. Maternal chronic and acute malnutrition appear to be associated with SGA outcomes. Because of high SGA prevalence in South Asia and the increased neonatal and infant mortality risk associated with SGA, there is an urgent need to intervene with effective interventions.     

Status of infants at birth and risk for adverse neonatal events and long-term sequelae: a study in low birth weight infants

We evaluated the relationship of infant status at birth to neonatal morbidity and long-term development in 246 low birth weight infants (600 to 1750 gm). Nineteen percent of infants had 1-minute Apgar scores of less than or equal to 3, and 8% had an umbilical artery pH of less than or equal to 7.2. Acidosis was associated with an increased risk of grade 3 to 4 intracranial hemorrhage (odds ratio = 3.3). Low 1-minute Apgar score was associated with an increased risk of death (odds ratio = 4.8). Grade 3 to 4 intracranial hemorrhage was a strong risk factor for cerebral palsy among survivors (odds ratio = 16.1), as was low 1-minute Apgar score (odds ratio = 2.9). Only 15% of cases of cerebral palsy in this study were associated with acidosis at birth.