Phenotypic Classification of preterm Birth Among Multiparous Women: A Population-Based Cohort Study.

OBJECTIVE: The Global Alliance to Prevent Prematurity and Stillbirth developed a phenotypic classification for preterm birth using clinical presentation (rather than risk factors) to improve surveillance. The objective of this study was to determine distributions of preterm birth phenotypes and associations with Caesarean section, low Apgar score, and neonatal death in multiparous women, stratifying by first versus recurrent preterm births. METHODS: This population-based cohort study used the Better Outcomes Registry and Network (BORN) of multiparous women giving birth in hospital with a singleton after 20 weeks in Ontario from 2012 to 2014 (Canadian Task Force Classification II-2). RESULTS: In multiparous women with preterm birth, 29.6% had a history of recurrence, of whom 66.2% had at least one clinical condition associated with the phenotypic model, compared with 63.5% of first preterm births. In recurrent preterm births, criteria for maternal, fetal, and placental conditions were met in 44.5%, 37.9%, and 8.2%, respectively, compared with 36.8%, 39.0%, and 10.4%, respectively, of first preterm births. Associations of preterm birth with Caesarean section, low Apgar score, and neonatal death varied across clinical conditions but were similar between first and recurrent preterm births; for example, for recurrent preterm birth, Caesarean section for maternal, fetal, and placental conditions had odds ratios of 1.66 (95% confidence interval [CI] 1.32-2.07), 1.09 (95% CI 0.80-1.49), and 3.92 (95% CI 1.98-7.78), compared with first preterm birth odds ratios of 1.21 (95% CI 1.03-1.41), 0.92 (95% CI 0.77-1.10), and 6.24 (95% CI 4.07-9.56). CONCLUSION: This study provides novel evidence of the utility of the preterm birth phenotypic classification model by using stratification for previous preterm birth, a robust predictor-with variation in phenotypes in initial and recurrent preterm births.

Phenotypic Classification of Preterm Birth Among Nulliparous Women: A Population-Based Cohort Study.

OBJECTIVE: A classification model based on preterm birth clinical presentations (phenotypes) was proposed at the International Conference on Prematurity and Stillbirth, with calls for validation. This study sought to determine the distribution of clinical phenotypes of preterm birth among nulliparous women, their corresponding associations with maternal characteristics, and the odds ratios (ORs) of preterm Caesarean section and other adverse outcomes. METHODS: A population-based cohort study was performed of all nulliparous women with singleton pregnancies (>20 weeks) who gave birth in a hospital in Ontario between 2012 and 2014. Logistic regression models were used to estimate adjusted ORs (Canadian Task Force Classification II-2). RESULTS: Among 113 942 nulliparous women, 6.1% delivered at <37 weeks, at a mean gestational age of 33.9 weeks. Of those women, 34.1% did not meet the criteria for the presence of any clinical phenotype; 42.3% had one maternal, fetal, or placental condition; 22.3% had two clinical conditions; and 1.3% had three clinical conditions. The most common preterm birth phenotypes were worsening of maternal diseases (24.0%), intrauterine growth restriction (23.5%), and fetal distress (23.0%). Compared with preterm births without any significant clinical phenotype, those with maternal, fetal, or placental phenotypes were associated with increased odds of Caesarean section (adjusted ORs 2.70 [95% confidence interval [CI] 2.30-3.17], 1.66 [95% CI 1.36-2.03], and 6.49 [95% CI 4.29-9.80], respectively). CONCLUSION: Approximately two thirds of nulliparous preterm births were grouped into distinct clinical phenotypes. This study demonstrated that outcomes varied across phenotypes, thus providing evidence of benefit for the phenotypic classification model.

Opium use during pregnancy and infant size at birth: a cohort study.

BACKGROUND: The reported positive association between opiatic drug use during pregnancy and adverse pregnancy outcomes might be confounded by other factors related to high-risk behaviors, including the use of other harmful substances. In rural areas of Iran, opium use during pregnancy is relatively common among women who otherwise do not have a hazardous lifestyle, which reduces the risk of residual confounding and increasing the possibility to identify its effects. We aimed to examine the association of antenatal exposure to opium with risks of small for gestational age, short birth length, and small head circumference at birth. METHOD: In this cohort study in the rural area of the Golestan province, Iran, we randomly selected 920 women who were exposed to opium during pregnancy and 920 unexposed women during 2008-2010. Log-binomial regression was used to estimate risk ratios (RR) and 95% confidence intervals (CI) for the associations between prenatal exposure to opium and risks of small for gestational age, short birth length, and small head circumference at birth. RESULTS: Compared with non-use of opium and tobacco during pregnancy, using opium only and dual use of opium and tobacco were associated with increased risks of small for gestational age at births (RR = 1.71; 95% CI 1.34-2.18 and RR = 1.62; 95% CI 1.13-2.30, respectively). Compared with non-use of opium and tobacco, exposure to only opium or dual use of opium and tobacco were also associated with more than doubled increased risks of short birth length, and small head circumference in term infants. CONCLUSION: Maternal opium use during pregnancy is associated with increased risks of giving birth to a small for gestational age infant, as well as a term infant with short birth length or small head circumference.

Opium use during pregnancy and risk of preterm delivery: A population-based cohort study.

BACKGROUND: Use of narcotic or "recreational" drugs has been associated with adverse pregnancy outcomes such as preterm delivery. However, the associations might be confounded by other factors related to high-risk behaviours. This is the first study to investigate the association between traditional opium use during pregnancy and risk of preterm delivery. METHOD AND FINDINGS: We performed a population-based cohort study in the rural areas of the Golestan province, Iran between 2008 and 2010. We randomly selected 920 women who used (usually smoked) opium during pregnancy and 920 women who did not. Logistic regression models were used to estimate odds ratios (OR) and 95% confidence intervals (CI) for the associations between the opium use during pregnancy and preterm delivery and adjustment was made for potential confounding factors. This study shows compared with non-use of opium and tobacco, use of only opium during pregnancy was associated with an increased risk of preterm delivery (OR = 1.56; 95% CI 1.05-2.32), and the risk was more than two-fold increased among dual users of opium and tobacco (OR = 2.31; 95% CI 1.37-3.90). We observed that opium use only was associated with a doubled risk for preterm caesarean delivery (OR = 2.05; 95% CI 1.10-3.82) but not for preterm vaginal delivery (OR = 1.25; 95% CI 0.75-2.07). Dual use of opium and tobacco was associated with a substantially increased risk of vaginal preterm delivery (OR = 2.58; 95% CI 1.41-4.71). CONCLUSIONS: Opium use during pregnancy among non-tobacco smokers is associated with an increased risk of preterm caesarean delivery, indicating an increased risk of a compromised foetus before or during labour. Women who use both opium and smoked during pregnancy have an increased risk of preterm vaginal delivery, indicating an increased risk of spontaneous preterm delivery.

Maternal haemoglobin concentrations before and during pregnancy and stillbirth risk: a population-based case-control study.

BACKGROUND: Results of previous studies on the association between maternal haemoglobin concentration during pregnancy and stillbirth risk are inconclusive. It is not clear if haemoglobin concentration before pregnancy has a role. Using prospectively collected information from pre-pregnancy and antenatal visits, we investigated associations of maternal haemoglobin concentrations before and during pregnancy and haemoglobin dilution with stillbirth risk. METHODS: In a population-based case-control study from rural Golestan, a province in northern Iran, we identified 495 stillbirths (cases) and randomly selected 2,888 control live births among antenatal health-care visits between 2007 and 2009. Using logistic regression, we estimated associations of maternal haemoglobin concentrations, haemoglobin dilution at different stages of pregnancy, with stillbirth risk. RESULTS: Compared with normal maternal haemoglobin concentration (110-120 g/l) at the end of the second trimester, high maternal haemoglobin concentration (≥140 g/l) was associated with a more than two-fold increased stillbirth risk (OR = 2.31, 95 % CI [1.30-4.10]), while low maternal haemoglobin concentration (<110 g/l) was associated with a 37 % reduction in stillbirth risk. Haemoglobin concentration before pregnancy was not associated with stillbirth risk. Decreased haemoglobin concentration, as measured during pregnancy (OR = 0.61, 95 % CI [0.46, 0.80]), or only during the second trimester (OR = 0.75, 95 % CI [0.62, 0.90]), were associated with reduced stillbirth risk. The associations were essentially similar for preterm and term stillbirths. CONCLUSIONS: Haemoglobin concentration before pregnancy is not associated with stillbirth risk. High haemoglobin level and absence of haemoglobin dilution during pregnancy could be considered as indicators of a high-risk pregnancy.

Consanguineous marriage, prepregnancy maternal characteristics and stillbirth risk: a population-based case-control study.

INTRODUCTION: Consanguineous marriage is associated with increased risks for congenital anomalies, low birthweight, and other adverse perinatal outcomes. In this population-based, case-control study we investigated the association between consanguineous marriage (first-cousin marriage) and stillbirth risk, using prospectively collected information from prepregnancy visits. MATERIAL AND METHODS: From 2007 to 2009, we identified 283 stillbirths (cases) and 2088 randomly selected live control births through prepregnancy visits in rural Golestan, Iran. The associations between consanguinity and prepregnancy maternal characteristics and stillbirth risk were examined using multivariate logistic regression. RESULTS: The rate of consanguineous marriage was 19.4% among cases and 13.6% among controls. Consanguinity was associated with increased stillbirth risk [odds ratio (OR) 1.53; 95% CI 1.10-2.14]. The association was significantly increased for preterm stillbirth (< 37 gestational weeks) (OR 2.43; 95% CI 1.46-4.04) but not for term stillbirth (≥ 37 weeks) (OR 1.14; 95% CI 0.75-1.74). Low and high maternal age, underweight, obesity, nulliparity, a history of infertility or miscarriage, previous obstetric complications (preeclampsia, preterm delivery, and stillbirth in previous pregnancies) were also associated with increased stillbirth risks. CONCLUSIONS: Consanguineous marriage is associated with increased risk of stillbirth, particularly preterm stillbirth. Findings for other maternal risk factors for stillbirth in rural Iran are consistent with previously reported findings from high-income countries.