Hypertensive disorders of pregnancy include chronic hypertension, gestational hypertension, pre-eclampsia and chronic hypertension with superimposed pre-eclampsia. Pre-eclampsia complicates about 3% ...of pregnancies, and all hypertensive disorders affect about five to 10% of pregnancies. Secular increases in chronic hypertension, gestational hypertension and pre-eclampsia have occurred as a result of changes in maternal characteristics (such as maternal age and pre-pregnancy weight), whereas declines in eclampsia have followed widespread antenatal care and use of prophylactic treatments (such as magnesium sulphate). Determinants of pre-eclampsia rates include a bewildering array of risk and protective factors, including familial factors, sperm exposure, maternal smoking, pre-existing medical conditions (such as hypertension, diabetes mellitus and anti-phospholipid syndrome), and miscellaneous ones such as plurality, older maternal age and obesity. Hypertensive disorders are associated with higher rates of maternal, fetal and infant mortality, and severe morbidity, especially in cases of severe pre-eclampsia, eclampsia and haemolysis, elevated liver enzymes and low platelets syndrome.
OBJECTIVE:To examine the association between interpregnancy interval and maternal–neonate health when matching women to their successive pregnancies to control for differences in maternal risk ...factors and compare these results with traditional unmatched designs.
METHODS:We conducted a retrospective cohort study of 38,178 women with three or more deliveries (two or greater interpregnancy intervals) between 2000 and 2015 in British Columbia, Canada. We examined interpregnancy interval (0–5, 6–11, 12–17, 18–23 reference, 24–59, and 60 months or greater) in relation to neonatal outcomes (preterm birth less than 37 weeks of gestation, small-for-gestational-age birth less than the 10th centile, use of neonatal intensive care, low birth weight less than 2,500 g) and maternal outcomes (gestational diabetes, beginning the subsequent pregnancy obese body mass index 30 or greater, and preeclampsia–eclampsia). We used conditional logistic regression to compare interpregnancy intervals within the same mother and unconditional (unmatched) logistic regression to enable comparison with prior research.
RESULTS:Analyses using the traditional unmatched design showed significantly increased risks associated with short interpregnancy intervals (eg, there were 232 preterm births 12.8% in 0–5 months compared with 501 8.2% in the 18–23 months reference group; adjusted odds ratio OR for preterm birth 1.53, 95% confidence interval CI 1.35–1.73). However, these risks were eliminated in within-woman matched analyses (adjusted OR for preterm birth 0.85, 95% CI 0.71–1.02). Matched results indicated that short interpregnancy intervals were significantly associated with increased risk of gestational diabetes (adjusted OR 1.35, 95% CI 1.02–1.80 for 0–5 months) and beginning the subsequent pregnancy obese (adjusted OR 1.61, 95% CI 1.05–2.45 for 0–5 months and adjusted OR 1.43, 95% CI 1.10–1.87 for 6–11 months).
CONCLUSION:Previously reported associations between short interpregnancy intervals and adverse neonatal outcomes may not be causal. However, short interpregnancy interval is associated with increased risk of gestational diabetes and beginning a subsequent pregnancy obese.
Random measurement error is a pervasive problem in medical research, which can introduce bias to an estimate of the association between a risk factor and a disease or make a true association ...statistically non-significant. Hutcheon and colleagues explain when, why, and how random measurement error introduces bias and provides strategies for researchers to minimise the problem
Abstract Purpose To illustrate how conditional growth percentiles can be adapted for use to systematically identify implausible measurements in growth trajectory data. Methods The use of conditional ...growth percentiles as a tool to assess serial weight data was reviewed. The approach was applied to 86,427 weight measurements (kg) taken between birth and age 6.5 years in 8217 girls participating in the Promotion of Breast Feeding Intervention Trial in Belarus. A conditional mean and variance was calculated for each weight measurement, which reflects the expected weight at a current visit given the girl's previous weights. Measurements were flagged as outliers if they were more than 4 standard deviation (SD) above or below the expected (conditional) weight. Results The method identified 234 weight measurements (0.3%) from 216 girls as potential outliers. Review of these trajectories confirmed the implausibility of the flagged measurements, and that the approach identified observations that would not have been identified using a conventional cross-sectional approach (±4 SD of the population mean) for identifying implausible values. Stata code to implement the approach is provided. Conclusions Conditional growth percentiles can be used to systematically identify implausible values in growth trajectory data and may be particularly useful for large data sets where the high number of trajectories makes ad hoc approaches unfeasible.
BACKGROUND:Fetal growth standards (prescriptive charts derived from low-risk pregnancies) are theoretically better tools to monitor fetal growth than conventional references. We examined how ...modifying chart inclusion criteria influenced the resulting curves.
METHODS:We summarized estimated fetal weight (EFW) distributions from a hospital’s routine 32-week ultrasound in all nonanomalous singleton fetuses (reference) and in those without maternal–fetal conditions affecting fetal growth (standard). We calculated EFWs for the 3rd, 5th, 10th, and 50th percentiles, and the proportion of fetuses each chart classified as small for gestational age.
RESULTS:Of 2309 fetuses in our reference, 690 (30%) met the standard’s inclusion criteria. There were no meaningful differences between the EFW distributions of the reference and standard curves (50th percentile1989 g reference vs. 1968 g standard; 10th percentile1711 g reference vs. 1710 g standard), or the proportion of small for gestational age fetuses (both 9.9%).
CONCLUSIONS:In our study, there was little practical difference between a fetal growth reference and standard for detecting small infants.
Background
The external validity of randomised trials can be compromised when trial participants differ from real‐world populations. In the Antenatal Late Preterm Steroids (ALPS) trial of antenatal ...corticosteroids at late preterm ages, participants had systematically younger gestational ages than those outside the trial setting. As risk of respiratory morbidity (the primary trial outcome) is higher at younger gestations, absolute benefits of corticosteroids calculated in the trial population may overestimate real‐world treatment benefits.
Objectives
To estimate the real‐world absolute risk reduction and number‐needed‐to‐treat (NNT) for antenatal corticosteroids at late preterm ages, accounting for gestational age differences between the ALPS and real‐world populations.
Methods
Individual participant data from the ALPS trial (which recruited 2831 women with imminent preterm birth at 34+0 to 36+5 weeks') was appended to population‐based data for 15,741 women admitted for delivery between 34+0 and 36+5 weeks' from British Columbia, Canada, 2000–2013. We used logistic regression to calculate inverse odds of sampling weights for each trial participant and re‐estimated treatment effects of corticosteroids on neonatal respiratory morbidity in ALPS participants, weighted to reflect the gestational age distribution of the population‐based (real‐world) sample.
Results
The real‐world absolute risk reduction was estimated to be −2.2 (95% CI −4.6, 0.0) cases of respiratory morbidity per 100, compared with −2.8 (95% CI −5.3, −0.3) in original trial data. Corresponding NNTs were 46 in the real‐world setting vs 35 in the trial. Our focus on absolute measures also highlighted that the benefits of antenatal corticosteroids may be meaningfully greater at 34 weeks vs. 36 weeks (e.g., risk reductions of −3.7 vs. −1.2 per 100 respectively).
Conclusions
The absolute risk reductions and NNTs associated with antenatal corticosteroid administration at late preterm ages estimated in our study may be more appropriate for patient counselling as they better reflect the anticipated benefits of treatment when used in a real‐world situation.
BACKGROUND:Women with a history of certain pregnancy complications are at higher risk for cardiovascular (CVD) disease. However, most clinical guidelines only recommend postpartum follow-up of those ...with a history of preeclampsia, gestational diabetes mellitus, or preterm birth. This systematic review was undertaken to determine if there is an association between a broader array of pregnancy complications and the future risk of CVD.
METHODS:We systematically searched PubMed, MEDLINE and EMBASE (via Ovid), CINAHL, and the Cochrane Library from inception to September 22, 2017, for observational studies of the association between the hypertensive disorders of pregnancy, placental abruption, preterm birth, gestational diabetes mellitus, low birth weight, small-for-gestational-age birth, stillbirth, and miscarriage and subsequent CVD. Likelihood ratio meta-analyses were performed to generate pooled odds ratios (OR) and 95% intrinsic confidence intervals (ICI).
RESULTS:Our systematic review included 84 studies (28 993 438 patients). Sample sizes varied from 250 to 2 000 000, with a median follow-up of 7.5 years postpartum. The risk of CVD was highest in women with gestational hypertension (OR 1.7; 95% ICI, 1.3–2.2), preeclampsia (OR 2.7; 95% ICI, 2.5–3.0), placental abruption (OR 1.8; 95% ICI, 1.4–2.3), preterm birth (OR 1.6; 95% ICI, 1.4–1.9), gestational diabetes mellitus (OR 1.7; 95% ICI, 1.1–2.5), and stillbirth (OR 1.5; 95% ICI, 1.1–2.1). A consistent trend was seen for low birth weight and small-for-gestational-age birth weight but not for miscarriage.
CONCLUSIONS:Women with a broader array of pregnancy complications, including placental abruption and stillbirth, are at increased risk of future CVD. The findings support the need for assessment and risk factor management beyond the postpartum period.
To estimate the absolute risks of adverse maternal and perinatal outcomes based on small differences in prepregnancy body mass (eg, 10% of body mass or 10-20 pounds).
This population-based cohort ...study (N=226,958) was drawn from all singleton pregnancies in British Columbia (Canada) from 2004 to 2012. The relationships between prepregnancy body mass index (BMI) (as a continuous, nonlinear variable) and adverse pregnancy outcomes were examined using logistic regression models. Analyses were adjusted for maternal age, height, parity, and smoking in pregnancy. Adjusted absolute risks of each outcome are reported according to incremental differences in prepregnancy BMI and weight in pounds.
A 10% difference in prepregnancy BMI was associated with at least a 10% lower risk of preeclampsia, gestational diabetes, indicated preterm delivery, macrosomia, and stillbirth. In contrast, larger differences in prepregnancy BMI (20-30% differences in BMI) were necessary to meaningfully reduce risks of cesarean delivery, shoulder dystocia, neonatal intensive care unit stay 48 hours or longer, and in-hospital newborn mortality. Prepregnancy BMI was not associated with risk of postpartum hemorrhage requiring intervention, severe maternal morbidity or maternal mortality, or spontaneous preterm delivery before 32 weeks of gestation.
These results can inform prepregnancy weight loss counseling by defining achievable weight loss goals for patients that may reduce their risk of poor perinatal outcomes.
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