scholarly journals 1273Confounding in the association between pregnancy complications and subsequent preterm birth

2021 ◽  
Vol 50 (Supplement_1) ◽  
Author(s):  
Jennifer Dunne ◽  
Gizachew Assefa Tessema ◽  
Gavin Pereira
Keyword(s):  
Preterm Birth ◽  
Pregnancy Complications ◽  
Retrospective Cohort ◽  
Maternal Obesity ◽  
Placental Abruption ◽  
Perinatal Death ◽  
Unmeasured Confounding ◽  
Unmeasured Confounder ◽  
Relative Risks ◽  
Underlying Causes

Abstract Background Underlying causal mechanisms that persist from pregnancy to pregnancy have potential to explain recurrence of pregnancy complications. We aimed to estimate the degree of confounding necessary to explain these associations. Methods This was a retrospective cohort study of women (n = 124,936) giving birth to their first and second singleton children in Western Australia 1998-2015, identified from the Midwives’ Notifications System. The investigated pregnancy complications were preterm birth (<37 gestational weeks), pre-eclampsia, placental abruption, small-for-gestational-age and perinatal death. Adjusted relative risks (RR) and confidence intervals (CI) were reported. We simulated maternal obesity and derived E-values, a method to determine the magnitude of unmeasured confounding. Results Complications in first pregnancy were associated with higher risk of preterm birth in second pregnancy. RR’s were significantly higher when the complication was recurrent. For the association between pre-eclampsia at first term birth and subsequent preterm birth, the RR increased from 1.2 (95% CI 1.05-1.41) to 11.9 (95% CI 9.52-11.49) when the complication reoccurred. E-values were 1.73 and 23.22 respectfully. Relative risks did not change after adjustment for maternal obesity. Conclusions The strong associations between pregnancy complications and preterm birth support the assumption of shared underlying causes that persist from pregnancy to pregnancy. High E-values suggest that recurrent confounding is unlikely, as any such unmeasured confounder would have to be uncharacteristically large. Key messages Well-established single confounders cannot explain away the strong associations between complications in first pregnancy and a subsequent preterm birth.

scholarly journals Risk of Infant Mortality Among Twins in Relation to Placental Abruption: Contributions of Preterm Birth and Restricted Fetal Growth

2005 ◽  
Vol 8 (5) ◽  
pp. 524-531 ◽  
Author(s):  
Cande V. Ananth ◽  
John C. Smulian ◽  
Neela Srinivas ◽  
Darios Getahun ◽  
Hamisu M. Salihu
Keyword(s):  
Preterm Birth ◽  
Infant Mortality ◽  
Fetal Growth ◽  
Gestational Age ◽  
Retrospective Cohort ◽  
Placental Abruption ◽  
The United States ◽  
Confounding Factors ◽  
Relative Risks ◽  
Strength Of Association

AbstractWhile preterm birth and restricted fetal growth are strongly associated with infant mortality, the extent to which these associations are modified by placental abruption remains unknown. A retrospective cohort study was carried out to examine the risk of infant mortality among twins in relation to abruption, and explore the independent contributions of preterm birth and restricted fetal growth to these associations. The study was restricted to women who had delivered twins at 22 weeks' gestation or more and fetuses weighing 500 grams or more in the United States (1989–2000). Risks of preterm birth (less than 37 weeks' gestation), fetal growth restriction and infant mortality, in relation to placental abruption, were evaluated. All analyses were adjusted for potential sociodemographic confounding factors. The association between restricted twin fetal growth and abruption was the strongest among the most severely growth-restricted babies (i.e., less than 1 centile), with the strength of association diminishing with increasing birthweight centiles. The risk of preterm birth among pregnancies with and without abruption were 80.1% and 51.9%, respectively (relative risk [RR] 1.5, 95% confidence interval [CI] 1.4–1.6). The risk of small-for-gestational-age (SGA; birthweight of less than the 10th centile for gestational age) among abruption and nonabruption births was 11.7% and 9.2%, respectively (RR 1.3, 95% CI 1.2–1.4). Compared with twins of the appropriate growth delivered at term, the relative risks for infant mortality in the presence of abruption were 9.9 (95% CI 5.4–18.2) for term-SGA, 25.0 (95% CI 22.3–28.1) for preterm-non-SGA, and 36.2 (95% CI 28.4–46.1) for preterm-SGA births. The association between infant mortality and abruption among twins appears largely mediated through preterm birth, and to a lesser extent, through SGA. The association between fetal growth and abruption is strongest among the severely growth-restricted babies, suggesting that the origins of placental abruption may develop in early pregnancy.

scholarly journals Women with a History of Recurrent Pregnancy Loss Are a High-Risk Population for Adverse Obstetrical Outcome: A Retrospective Cohort Study

2021 ◽  
Vol 10 (2) ◽  
pp. 179
Author(s):  
Emma Rasmark Roepke ◽  
Ole Bjarne Christiansen ◽  
Karin Källén ◽  
Stefan R. Hansson
Keyword(s):  
Cohort Study ◽  
Preterm Birth ◽  
Pregnancy Complications ◽  
Pregnancy Loss ◽  
Recurrent Pregnancy Loss ◽  
Placental Abruption ◽  
Late Pregnancy ◽  
High Risk Population ◽  
Risk Population ◽  
Increased Risk

Recurrent pregnancy loss (RPL), defined as three or more consecutive miscarriages, is hypothesized to share some of the same pathogenic factors as placenta-associated disorders. It has been hypothesized that a defect implantation causes pregnancy loss, while a partially impaired implantation may lead to late pregnancy complications. The aim of this retrospective register-based cohort study was to study the association between RPL and such disorders including pre-eclampsia, stillbirth, small for gestational age (SGA) birth, preterm birth and placental abruption. Women registered with childbirth(s) in the Swedish Medical Birth Register (MFR) were included in the cohort. Pregnancies of women diagnosed with RPL (exposed) in the National Patient Register (NPR), were compared with pregnancies of women without RPL (unexposed/reference). Obstetrical outcomes, in the first pregnancy subsequent to the diagnosis of RPL (n = 4971), were compared with outcomes in reference-pregnancies (n = 57,410). Associations between RPL and placental dysfunctional disorders were estimated by odds ratios (AORs) adjusting for confounders, with logistic regression. RPL women had an increased risk for pre-eclampsia (AOR 1.45; 95% CI; 1.24–1.69), stillbirth <37 gestational weeks (GWs) (AOR 1.92; 95% CI; 1.22–3.02), SGA birth (AOR 1.97; 95% CI; 1.42–2.74), preterm birth (AOR 1.46; 95% CI; 1.20–1.77), and placental abruption <37 GWs (AOR 2.47; 95% CI; 1.62–3.76) compared with pregnancies by women without RPL. Women with RPL had an increased risk of pregnancy complications associated with placental dysfunction. This risk population is, therefore, in need of improved antenatal surveillance.

scholarly journals Benefits of not smoking during pregnancy for Australian Aboriginal and Torres Strait Islander women and their babies: a retrospective cohort study using linked data

BMJ Open ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. e032763 ◽  
Author(s):  
Carol McInerney ◽  
Ibinabo Ibiebele ◽  
Jane B Ford ◽  
Deborah Randall ◽  
Jonathan M Morris ◽  
...  
Keyword(s):  
Preterm Birth ◽  
Gestational Age ◽  
Small For Gestational Age ◽  
Lower Risk ◽  
Perinatal Death ◽  
Perinatal Outcomes ◽  
Smoking During Pregnancy ◽  
Relative Risks ◽  
South Wales ◽  
Adverse Perinatal Outcomes

ObjectivesTo provide evidence for targeted smoking cessation policy, the aim of this study was to compare pregnancy outcomes of Aboriginal mothers who reported not smoking during pregnancy with Aboriginal mothers who reported smoking during pregnancy.DesignPopulation based retrospective cohort study using linked data.SettingNew South Wales, the most populous Australian state.Population18 154 singleton babies born to 13 477 Aboriginal mothers between 2010 and 2014 were identified from routinely collected New South Wales datasets. Aboriginality was determined from birth records and from four linked datasets through an Enhanced Reporting of Aboriginality algorithm.ExposureNot smoking at any time during pregnancy.Main outcome measuresUnadjusted and adjusted relative risks (aRR) and 95% CIs from modified Poisson regression were used to examine associations between not smoking during pregnancy and maternal and perinatal outcomes including severe morbidity, inter-hospital transfer, perinatal death, preterm birth and small-for-gestational age. Population attributable fractions (PAFs) were calculated using adjusted relative risks.ResultsCompared with babies born to mothers who smoked during pregnancy, babies born to non-smoking mothers had a lower risk of all adverse perinatal outcomes including perinatal death (aRR=0.58, 95% CI 0.44 to 0.76), preterm birth (aRR=0.58, 95% CI 0.53 to 0.64) and small-for-gestational age (aRR=0.35, 95% CI 0.32 to 0.39). PAFs (%) were 27% for perinatal death, 26% for preterm birth and 48% for small-for-gestational-age. Compared with women who smoked during pregnancy (n=8919), those who did not smoke (n=9235) had a lower risk of being transferred to another hospital (aRR=0.76, 95% CI 0.66 to 0.89).ConclusionsBabies born to women who did not smoke during pregnancy had a lower risk of adverse perinatal outcomes. Rates of adverse outcomes among Aboriginal non-smokers were similar to those among the general population. These results quantify the proportion of adverse perinatal outcomes due to smoking and highlight why effective smoking cessation programme are urgently required for this population.

scholarly journals 631Benefits of not smoking during pregnancy for Aboriginal women and their babies

2021 ◽  
Vol 50 (Supplement_1) ◽  
Author(s):  
Siranda Torvaldsen ◽  
Ibinabo Ibiebele ◽  
Jane Ford ◽  
Deborah Randall ◽  
Jonathan Morris ◽  
...  
Keyword(s):  
Preterm Birth ◽  
Gestational Age ◽  
Small For Gestational Age ◽  
Lower Risk ◽  
Perinatal Death ◽  
Perinatal Outcomes ◽  
Smoking During Pregnancy ◽  
Relative Risks ◽  
Aboriginal Women ◽  
Adverse Perinatal Outcomes

Abstract Background To provide evidence for targeted smoking cessation policy, the aim of this study was to compare pregnancy outcomes of Aboriginal mothers who reported not smoking during pregnancy with those who reported smoking. Methods This population-based retrospective cohort study used linked data from routinely collected datasets. Not smoking during pregnancy was the exposure of interest among all New South Wales Aboriginal women who became mothers of singleton babies in 2010–2014. Unadjusted and adjusted relative risks (aRR) and 95%CIs from modified Poisson regression were used to examine associations between not smoking during pregnancy and maternal and perinatal outcomes including severe morbidity, inter-hospital transfer, perinatal death, preterm birth and small-for-gestational age. Population attributable fractions (PAFs) were calculated using adjusted relative risks. Results Compared with babies born to mothers who smoked during pregnancy, babies born to non-smoking mothers had a lower risk of all adverse perinatal outcomes including perinatal death (aRR=0.58, 95%CI 0.44–0.76), preterm birth (aRR=0.58, 95%CI 0.53–0.64) and small-for-gestational age (aRR=0.35, 95%CI 0.32–0.39). PAFs(%) were 27% for perinatal death, 26% for preterm birth and 48% for small-for-gestational-age. Compared with women who smoked during pregnancy (n = 8,919), those who did not smoke (n = 9,235) had a lower risk of being transferred to another hospital (aRR=0.76, 95%CI 0.66–0.89). Conclusions Babies born to women who did not smoke had much lower risks of all adverse perinatal outcomes. Key messages Between a quarter and a half of adverse perinatal outcomes in this population could potentially be prevented by an effective smoking cessation program.

Impact of the nitric oxide-donor pentaerythrityl-tetranitrate on perinatal outcome in risk pregnancies: a prospective, randomized, double-blinded trial

2014 ◽  
Vol 42 (4) ◽  
Author(s):  
Ekkehard Schleussner ◽  
Thomas Lehmann ◽  
Christiane Kähler ◽  
Uwe Schneider ◽  
Dietmar Schlembach ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
At Risk ◽  
Preterm Birth ◽  
Placental Abruption ◽  
Perinatal Death ◽  
Adverse Pregnancy Outcome ◽  
Nitric Oxide Donor ◽  
Adjusted Relative Risk ◽  
Placental Perfusion ◽  
Double Blinded

AbstractIntrauterine growth restriction (IUGR) and preeclampsia (PE) are associated with impaired placentation. Patients who are at risk of developing both these disorders can be identified by abnormal uterine artery Doppler at mid-trimester pregnancy. Nitric oxide (NO)-donors like pentaerithrityl-tetranitrate (PETN) reduce the impedance in the uteroplacental vessels and possess protecting effects on the endothelium. We tested the effectiveness of the NO-donor PETN for secondary prevention of IUGR, PE, and preterm birth in pregnancies at risk. Some 111 women who presented with abnormal placental perfusion at 19–24 weeks of gestation (w.o.g.) were included into a prospective, randomized, placebo-controlled, double-blinded study. The primary endpoint was IUGR and/or perinatal death. Secondary endpoints were preterm birth, PE, and placental abruption. Pentaerithrityl-tetranitrate significantly decreased the risk for IUGR and/or perinatal death [adjusted relative risk (RR) 0.410; 95% confidence interval, CI, 0.184–0.914] and for IUGR (adjusted RR 0.436; 95% CI 0.196–0.970). Preterm birth before 32 w.o.g. (adjusted RR 0.204; 95% CI 0.052–0.801) was reduced, but not the risk for PE. No placental abruption occurred in the PETN, but five occurred in the placebo group. These results suggest that secondary prophylaxis of adverse pregnancy outcome might be feasible in pregnancies exhibiting abnormal placentation using PETN.

scholarly journals A new customised placental weight standard redefines the relationship between maternal obesity and extremes of placental size and is more closely associated with pregnancy complications than an existing population standard

2019 ◽  
Vol 11 (4) ◽  
pp. 350-359
Author(s):  
Jacqueline M. Wallace ◽  
Joeleita P. Agard ◽  
Graham W. Horgan
Keyword(s):  
Pregnancy Complications ◽  
Maternal Obesity ◽  
Population Based ◽  
Multiple Regression Model ◽  
Placental Weight ◽  
Morbidly Obese ◽  
Obese Women ◽  
Entire Cohort ◽  
Multiparous Women ◽  
The Difference

AbstractPlacental weight is a valuable indicator of its function, predicting both pregnancy outcome and lifelong health. Population-based centile charts of weight-for-gestational-age and parity are useful for identifying extremes of placental weight but fail to consider maternal size. To address this deficit, a multiple regression model was fitted to derive coefficients for predicting normal placental weight using records from healthy pregnancies of nulliparous/multiparous women of differing height and weight (n = 107,170 deliveries, 37–43 weeks gestation). The difference between actual and predicted placental weight generated a z-score/individual centile for the entire cohort including women with pregnancy complications (n = 121,591). The association between maternal BMI and placental weight extremes defined by the new customised versus population-based standard was investigated by logistic regression, as was the association between low placental weight and pregnancy complications. Underweight women had a greater risk of low placental weight [<10thcentile, OR 1.84 (95% CI 1.66, 2.05)] and obese women had a greater risk of high placental weight [>90th centile, OR 1.98 (95% CI 1.88, 2.10)] using a population standard. After customisation, the risk of high placental weight in obese/morbidly obese women was attenuated [OR 1.17 (95% CI 1.09, 1.25)]/no longer significant, while their risk of low placental weight was 59%–129% higher (P < 0.001). The customised placental weight standard was more closely associated with stillbirth, hypertensive disease, placental abruption and neonatal death than the population standard. Our customised placental weight standard reveals higher risk of relative placental growth restriction leading to lower than expected birthweights in obese women, and a stronger association between low placental weight and pregnancy complications generally. Further, it provides an alternative tool for defining placental weight extremes with implications for the placental programming of chronic disease.

scholarly journals Preterm Delivery; Who Is at Risk?

2021 ◽  
Vol 10 (11) ◽  
pp. 2279
Author(s):  
Dvora Kluwgant ◽  
Tamar Wainstock ◽  
Eyal Sheiner ◽  
Gali Pariente
Keyword(s):  
Risk Factors ◽  
Preterm Birth ◽  
Prenatal Care ◽  
Recurrent Pregnancy Loss ◽  
Placental Abruption ◽  
Placenta Previa ◽  
Population Based ◽  
Perinatal Morbidity ◽  
Multiple Gestations ◽  
Extremely Preterm

Preterm birth (PTB) is the leading cause of perinatal morbidity and mortality. Adverse effects of preterm birth have a direct correlation with the degree of prematurity, in which infants who are born extremely preterm (24–28 weeks gestation) have the worst outcomes. We sought to determine prominent risk factors for extreme PTB and whether these factors varied between various sub-populations with known risk factors such as previous PTB and multiple gestations. A population-based retrospective cohort study was conducted. Risk factors were examined in cases of extreme PTB in the general population, as well as various sub-groups: singleton and multiple gestations, women with a previous PTB, and women with indicated or induced PTB. A total of 334,415 deliveries were included, of which 1155 (0.35%) were in the extreme PTB group. Placenta previa (OR = 5.8, 95%CI 4.14–8.34, p < 0.001), multiple gestations (OR = 7.7, 95% CI 6.58–9.04, p < 0.001), and placental abruption (OR = 20.6, 95%CI 17.00–24.96, p < 0.001) were the strongest risk factors for extreme PTB. In sub-populations (multiple gestations, women with previous PTB and indicated PTBs), risk factors included placental abruption and previa, lack of prenatal care, and recurrent pregnancy loss. Singleton extreme PTB risk factors included nulliparity, lack of prenatal care, and placental abruption. Placental abruption was the strongest risk factor for extreme preterm birth in all groups, and risk factors did not differ significantly between sub-populations.

scholarly journals Can a Difference in Gestational Age According to Biparietal Diameter and Abdominal Circumference Predict Intrapartum Placental Abruption?

2021 ◽  
Vol 10 (11) ◽  
pp. 2413
Author(s):  
Jee-Youn Hong ◽  
Jin-Ha Kim ◽  
Seo-yeon Kim ◽  
Ji-Hee Sung ◽  
Suk-Joo Choi ◽  
...  
Keyword(s):  
Gestational Age ◽  
Odds Ratio ◽  
Retrospective Cohort ◽  
Maternal Age ◽  
Placental Abruption ◽  
Independent Predictor ◽  
Abdominal Circumference ◽  
Biparietal Diameter ◽  
Study Population ◽  
Independent Risk Factors

This study aimed to investigate whether a difference in gestational age according to biparietal diameter (BPD) and abdominal circumference (AC) could be a clinically useful predictor of placental abruption during the intrapartum period. This retrospective cohort study was based on singletons who were delivered after 32 + 0 weeks between July 2015 and July 2020. We only included cases with at least two antepartum sonographies available within 4 weeks of delivery (n = 2790). We divided the study population into two groups according to the presence or absence of placental abruption and compared the clinical variables. The incidence of placental abruption was 2.0% (56/2790) and was associated with an older maternal age, a higher rate of preeclampsia, and being small for the gestational age. A difference of >2 weeks in gestational age according to BPD and AC occurred at a higher rate in the placental abruption group compared to the no abruption group (>2 weeks, 21.4% (12/56) vs. 7.5% (205/2734), p < 0.001; >3 weeks, 12.5% (7/56) vs. 2.0% (56/2734), p < 0.001). Logistic regression analysis revealed that the differences of >2 weeks and >3 weeks were both independent risk factors for placental abruption (odds ratio (OR) (95% confidence interval), 2.289 (1.140–4.600) and 3.918 (1.517–9.771), respectively) after adjusting for maternal age, preeclampsia, and small for gestational age births. We identified that a difference in gestational age of >2 weeks between BPD and AC could be an independent predictor of placental abruption.

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