Temporal trends and predictors of gestational exposure to organophosphate ester flame retardants and plasticizers

BACKGROUND

Organophosphate esters (OPEs), used as flame retardants and plasticizers, are chemicals of concern for maternal and infant health. Prior studies examining temporal trends and predictors of OPE exposure are primarily limited by small sample sizes.

OBJECTIVES

Characterize temporal trends and predictors of OPE exposure biomarkers.

METHODS

We determined urinary concentrations of eight biomarkers of OPE exposure at three timepoints during pregnancy for participants in the LIFECODES Fetal Growth Study (n = 900), a nested case-cohort recruited between 2007 and 2018. We examined biomarker concentrations, their variability during pregnancy, and temporal trends over the study period. In addition, we identified sociodemographic and pregnancy characteristics associated with biomarker concentrations. Analyses were conducted using both the within-subject pregnancy geometric means and biomarker concentrations measured at individual study visits.

RESULTS

Five OPE biomarkers were detected in at least 60% of the study participants. Biomarkers were not strongly correlated with one another and intraclass correlation coefficients, measuring within-subject variability during pregnancy, ranged from 0.27 to 0.51. Biomarkers exhibited varying temporal trends across study years. For example, bis(1-chloro-2-propyl) phosphate (BCIPP) increased monotonically, whereas bis(1,3-dichloro-2-propyl) phosphate (BDCIPP) and diphenyl phosphate (DPHP), displayed non-monotonic trends with concentrations that peaked between 2011 and 2014. We observed associations between sociodemographic characteristics and OPE biomarkers. In general, concentrations of most OPE biomarkers were higher among participants from racial and ethnic minority populations, participants who were younger, had higher pre-pregnancy body mass index (BMI), and less than a college degree. We observed consistent results using either averaged or visit-specific biomarker concentrations.

SIGNIFICANCE

We observed widespread exposure to several OPEs and OPE biomarkers displayed varying temporal trends in pregnant people from 2007 to 2018. Concentrations of most OPE biomarkers varied according to sociodemographic factors, suggesting higher burdens of exposure among participants with higher pre-pregnancy BMI, those belonging to racial and ethnic minority populations, and lower educational attainment.

Temporal trends and predictors of phthalate, phthalate replacement, and phenol biomarkers in the LIFECODES Fetal Growth Study

BACKGROUND

Exposure to many phthalates and phenols is declining as replacements are introduced. There is little information on temporal trends or predictors of exposure to these newer compounds, such as phthalate replacements, especially among pregnant populations.

OBJECTIVE

Examine temporal trends and predictors of exposure to phthalates, phthalate replacements, and phenols using single- and multi-pollutant approaches.

METHODS

We analyzed data from 900 singleton pregnancies in the LIFECODES Fetal Growth Study, a nested case-cohort with recruitment from 2007 to 2018. We measured and averaged concentrations of 12 phthalate metabolites, four phthalate replacement metabolites, and 12 phenols in urine at three timepoints during pregnancy. We visualized and analyzed temporal trends and predictors of biomarker concentrations. To examine chemical mixtures, we derived clusters of individuals with shared exposure profiles using a finite mixture model and examined temporal trends and predictors of cluster assignment.

RESULTS

Exposure to phthalates and most phenols declined across the study period, while exposure to phthalate replacements (i.e., di(isononyl) cyclohexane-1,2-dicarboxylic acid, diisononyl ester [DINCH] and di-2-ethylhexyl terephthalate [DEHTP]) and bisphenol S (BPS) increased. For example, the sum of DEHTP biomarkers increased multiple orders of magnitude, with an average concentration of 0.92 ng/mL from 2007 to 2008 and 61.9 ng/mL in 2017-2018. Biomarkers of most chemical exposures varied across sociodemographic characteristics, with the highest concentrations observed in non-Hispanic Black or Hispanic participants relative to non-Hispanic White participants. We identified five clusters with shared exposure profiles and observed temporal trends in cluster membership. For example, at the end of the study period, a cluster characterized by high exposure to phthalate replacements was the most prevalent.

SIGNIFICANCE

In a large and well-characterized pregnancy cohort, we observed exposure to phthalate replacements and BPS increased over time while exposure to phthalates and other phenols decreased. Our results highlight the changing nature of exposure to consumer product chemical mixtures.

Risk of pre-eclampsia in patients with a maternal genetic predisposition to common medical conditions: a case-control study

OBJECTIVE

To assess whether women with a genetic predisposition to medical conditions known to increase pre-eclampsia risk have an increased risk of pre-eclampsia in pregnancy.

DESIGN

Case-control study.

SETTING AND POPULATION

Pre-eclampsia cases (n = 498) and controls (n = 1864) in women of European ancestry from five US sites genotyped on a cardiovascular gene-centric array.

METHODS

Significant single-nucleotide polymorphisms (SNPs) from 21 traits in seven disease categories (cardiovascular, inflammatory/autoimmune, insulin resistance, liver, obesity, renal and thrombophilia) with published genome-wide association studies (GWAS) were used to create a genetic instrument for each trait. Multivariable logistic regression was used to test the association of each continuous scaled genetic instrument with pre-eclampsia. Odds of pre-eclampsia were compared across quartiles of the genetic instrument and evaluated for significance.

MAIN OUTCOME MEASURES

Genetic predisposition to medical conditions and relationship with pre-eclampsia.

RESULTS

An increasing burden of risk alleles for elevated diastolic blood pressure (DBP) and increased body mass index (BMI) were associated with an increased risk of pre-eclampsia (DBP, overall OR 1.11, 95% CI 1.01-1.21, P = 0.025; BMI, OR 1.10, 95% CI 1.00-1.20, P = 0.042), whereas alleles associated with elevated alkaline phosphatase (ALP) were protective (OR 0.89, 95% CI 0.82-0.97, P = 0.008), driven primarily by pleiotropic effects of variants in the FADS gene region. The effect of DBP genetic loci was even greater in early-onset pre-eclampsia cases (at <34 weeks of gestation, OR 1.30, 95% CI 1.08-1.56, P = 0.005). For other traits, there was no evidence of an association.

CONCLUSIONS

These results suggest that the underlying genetic architecture of pre-eclampsia may be shared with other disorders, specifically hypertension and obesity.

TWEETABLE ABSTRACT

A genetic predisposition to increased diastolic blood pressure and obesity increases the risk of pre-eclampsia.

Commentary on a combined approach to the problem of developing biomarkers for the prediction of spontaneous preterm labor that leads to preterm birth

INTRODUCTION

Globally, preterm birth has replaced congenital malformation as the major cause of perinatal mortality and morbidity. The reduced rate of congenital malformation was not achieved through a single biophysical or biochemical marker at a specific gestational age, but rather through a combination of clinical, biophysical and biochemical markers at different gestational ages. Since the aetiology of spontaneous preterm birth is also multifactorial, it is unlikely that a single biomarker test, at a specific gestational age will emerge as the definitive predictive test.

METHODS

The Biomarkers Group of PREBIC, comprising clinicians, basic scientists and other experts in the field, with a particular interest in preterm birth have produced this commentary with short, medium and long-term aims: i) to alert clinicians to the advances that are being made in the prediction of spontaneous preterm birth; ii) to encourage clinicians and scientists to continue their efforts in this field, and not to be disheartened or nihilistic because of a perceived lack of progress and iii) to enable development of novel interventions that can reduce the mortality and morbidity associated with preterm birth.

RESULTS

Using language that we hope is clear to practising clinicians, we have identified 11 Sections in which there exists the potential, feasibility and capability of technologies for candidate biomarkers in the prediction of spontaneous preterm birth and how current limitations to this research might be circumvented.

DISCUSSION

The combination of biophysical, biochemical, immunological, microbiological, fetal cell, exosomal, or cell free RNA at different gestational ages, integrated as part of a multivariable predictor model may be necessary to advance our attempts to predict sPTL and PTB. This will require systems biological data using "omics" data and artificial intelligence/machine learning to manage the data appropriately. The ultimate goal is to reduce the mortality and morbidity associated with preterm birth.

Assisted reproductive technology and the risk of unplanned peripartum hysterectomy: analysis using propensity score matching

STUDY QUESTION

Is there an increased risk of unplanned peripartum hysterectomy in pregnancies with assissted reproductive technology compared to those without ART?

SUMMARY ANSWER

Although the absolute risks are low, there is an almost five-fold increased risk of unplanned peripartum hysterectomy and 1.7 more unplanned peripartum hysterectomies occur per 1000 deliveries in pregnancies with ART compared to those without ART.

WHAT IS KNOWN ALREADY

It has been reported that pregnancies with ART was associated with increased risk of peripartum hysterectomy in one case-control study and in one cohort study.

STUDY DESIGN, SIZE, DURATION

A retrospective cohort study was conducted using a birth cohort from 2014 and 2015 in the United States, which includes more than 7 million births. Propensity score (PS) matching was used to control for confounding.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Subjects were divided into two groups: pregnancies with and without ART. We calculated PSs with demographic, clinical and socioeconomic variables, and subjects were matched using the PS with a 1:1 ratio. Subjects comprised 43868 ART pregnancies and 43868 non-ART pregnancies after PS matching. The primary outcome of interest was the risk of unplanned peripartum hysterectomy which was compared by evaluating the relative risk and the risk difference between the two groups after PS matching.

MAIN RESULTS AND THE ROLE OF CHANCE

Baseline characteristics were similar between groups after PS matching. The risk of peripartum hysterectomy in women with ART was 4.947 times that of those without ART (0.0021 [94/43868] vs 0.0004 [19/43868]; 95% confidence interval [CI] 3.022-8.098). The risk difference between two groups was 0.0017 (95% CI 0.0012-0.0022).

LIMITATIONS, REASONS FOR CAUTION

There is a possibility of bias due to unmeasured confounding such as fibroids, previous history of uterine surgery and intrauterine procedures. Misclassification of the exposure and/or the outcome could also influence the results.

WIDER IMPLICATIONS OF THE FINDINGS

Although we found a five-fold increased risk of unplanned peripartum hysterectomy in pregnancies with ART compared to those without ART, the results should be interpreted with caution in a clinical context as the overall number and the absolute risk of unplanned peripartum hysterectomy are very low in either group (1/2325 in the non-ART group, and 1/468 in the ART group). However, it would be appropriate as future research agenda to explore mechanisms and/or etiology underlying this finding.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was used and there are no competing interests.

TRIAL REGISTRATION NUMBER

Not applicable.

Perinatal systemic inflammatory responses of growth-restricted preterm newborns

AIM

To compare the early post-natal pattern of systemic inflammation in growth-restricted infants born before the 28th week of gestation to that of appropriately grown peers.

METHODS

We measured the concentrations of 25 inflammation-related proteins in blood spots collected from 939 newborns during the first 2 post-natal weeks. We calculated the odds ratios (99% confidence intervals) that concentrations would be in the highest quartile.

RESULTS

Severely growth-restricted infants (birth weight Z-score <-2) were not at increased risk of systemic inflammation shortly after birth. On post-natal day 14, however, they were significantly more likely than their peers to have a CRP, IL-1β, IL-6, TNF-α, IL-8, MCP-4, ICAM-1, ICAM-3, E-SEL, MMP-9, VEGF-R2 and/or IGFBP-1 concentration in the highest quartile. These increased risks could not be attributed to delivery indication, bacteremia or duration of ventilation.

CONCLUSION

Growth-restricted preterm newborns appear to be at increased risk of elevated concentrations of inflammation-associated proteins by post-natal day 14.

Preterm severe preeclampsia in singleton and twin pregnancies

OBJECTIVE

We aimed to evaluate rates of delivery and clinical manifestations of preterm severe preeclampsia in singleton and twin gestations.

STUDY DESIGN

This retrospective cohort study included 86 765 deliveries from 2000 to 2009, including 3244 twins. Rates of delivery for severe preeclampsia among infants born 24 to 31+6, and 32 to 36+6 weeks gestation were calculated, and diagnostic criteria were compared.

RESULT

Re-term severe preeclampsia was more common in twin pregnancies (2.4% vs 0.4%, P<0.001, relative risk 5.70 (95% confidence interval 4.47 to 7.26)). This was also true for deliveries from 24 to 31+6 (0.8% vs 0.2%, P<0.001) and 32 to 36+6 weeks (1.7% vs 0.3%, P<0.001). Diagnostic criteria and disease manifestation including hemolysis elevated liver enzymes low platelet count syndrome, abruption and growth restriction were similar between groups.

CONCLUSION

Twin pregnancies are significantly more likely than singletons to be delivered preterm for severe preeclampsia. Diagnostic criteria and disease manifestation were similar in singletons and twins, at all gestational ages.

Antenatal antecedents of cognitive impairment at 24 months in extremely low gestational age newborns

BACKGROUND AND OBJECTIVES

Extremely low gestational age neonates are more likely than term infants to develop cognitive impairment. Few studies have addressed antenatal risk factors of this condition. We identified antenatal antecedents of cognitive impairment determined by the Mental Development Index (MDI) portion of the Bayley Scales of Infant Development, Second Edition (BSID-II), at 24 months corrected age.

METHODS

We studied a multicenter cohort of 921 infants born before 28 weeks of gestation during 2002 to 2004 and assessed their placentas for histologic characteristics and microorganisms. The mother was interviewed and her medical record was reviewed. At 24 months adjusted age, children were assessed with BSID-II. Multinomial logistic models were used to estimate odds ratios.

RESULTS

A total of 103 infants (11%) had an MDI <55, and 99 infants (11%) had an MDI between 55 and 69. No associations were identified between organisms recovered from the placenta and developmental delay. Factors most strongly associated with MDI <55 were thrombosis of fetal vessels (OR 3.1; 95% confidence interval [CI] 1.2, 7.7), maternal BMI >30 (OR 2.0; 95% CI 1.1, 3.5), maternal education ≤12 years (OR 3.4; 95% CI 1.9, 6.2), nonwhite race (OR 2.2; 95% CI 1.3, 3.8), birth weight z score < -2 (OR 2.8; 95% CI 1.1, 6.9), and male gender (OR 2.7; 95% CI 1.6, 4.5).

CONCLUSIONS

Antenatal factors, including thrombosis of fetal vessels in the placenta, severe fetal growth restriction, and maternal obesity, convey information about the risk of cognitive impairment among extremely premature newborns.

Pregnancy disorders that lead to delivery before the 28th week of gestation: an epidemiologic approach to classification

Epidemiologists have grouped the multiple disorders that lead to preterm delivery before the 28th week of gestation in a variety of ways. The authors sought to identify characteristics that would help guide how to classify disorders that lead to such preterm delivery. They enrolled 1,006 women who delivered a liveborn singleton infant of less than 28 weeks' gestation at 14 centers in the United States between 2002 and 2004. Each delivery was classified by presentation: preterm labor (40%), prelabor premature rupture of membranes (23%), preeclampsia (18%), placental abruption (11%), cervical incompetence (5%), and fetal indication/intrauterine growth restriction (3%). Using factor analysis (eigenvalue = 1.73) to compare characteristics identified by standardized interview, chart review, placental histology, and placental microbiology among the presentation groups, the authors found 2 broad patterns. One pattern, characterized by histologic chorioamnionitis and placental microbe recovery, was associated with preterm labor, prelabor premature rupture of membranes, placental abruption, and cervical insufficiency. The other, characterized by a paucity of organisms and inflammation but the presence of histologic features of dysfunctional placentation, was associated with preeclampsia and fetal indication/intrauterine growth restriction. Disorders leading to preterm delivery may be separated into two groups: those associated with intrauterine inflammation and those associated with aberrations of placentation.

Prenatal ultrasonography and the diagnosis of fetal cleft lip

OBJECTIVE

To determine the efficacy of obstetric ultrasonography in the detection of fetal cleft lip.

METHODS

The study population included all women who had a fetal anatomic survey with adequate visualization of the face and who gave birth at Brigham and Women's Hospital between January 1, 1990, and January 31, 2000. All neonates born with cleft lip were identified from the Brigham and Women's Active Malformation Surveillance Program. Confirmation of the anatomic defect was obtained from the pediatric record or from the pathologic report if the pregnancy was terminated or ended in miscarriage. Cases of isolated cleft palate were excluded. An ultrasonography database was used to identify all cases of cleft lip diagnosed before delivery. Maternal information regarding the pregnancy was abstracted from the medical record. Statistical significance was determined using the chi2 statistic for categorical variables and the t test for continuous variables.

RESULTS

A total of 56 confirmed cases of cleft lip were identified in the study population. Overall, 73% of the cases (41 of 56) were identified antenatally. Additional fetal anomalies were present in 54% of the cases (30 of 56). A comparison between those cases that were detected and those in which the diagnosis was missed showed that there was a significantly lower detection rate if the ultrasonography was performed before 20 weeks (12 [57%] of 21 versus 29 [83%] of 35; P = .035). There was no difference between the 2 groups in terms of maternal age or weight. Maternal parity, prior maternal abdominal surgery, the presence of a multiple gestation, or coexisting fetal anomalies did not significantly affect the detection rate. There was no difference in detection rate in the first half of the study period (1990-1995; 23 [72%] of 32) compared with the second half (1996-2000; 18 [76%] of 24; P = .79).

CONCLUSIONS

In this cohort of women, the rate of detection of fetal cleft lip was significantly lower when the anatomic survey was performed before 20 weeks' gestation. This difference could not be accounted for by such variables as prior maternal abdominal surgery, coexisting fetal anomalies, or improvements in ultrasonographic detection with time. We recommend that the anatomic survey for fetuses at high risk for this condition be performed after 20 weeks' gestation.

Neonatal outcome of infants born at 23 weeks' gestation

OBJECTIVE

To determine the neonatal outcome in accurately dated 23-week deliveries.

METHODS

We reviewed the records of consecutive births between 23 0/7 and 23 6/7 weeks at Brigham & Women's Hospital, Boston, Massachusetts, from January 1995 to December 1999. Women were excluded if they presented for elective termination or had known fetal death or poor dating criteria. Neonatal records were abstracted for mortality and short-term morbidity, including the respiratory distress syndrome (RDS), intraventricular hemorrhage, chronic lung disease, necrotizing enterocolitis, periventricular leukomalacia, and retinopathy of prematurity. Survival was defined as discharge from neonatal intensive care.

RESULTS

Thirty-three singleton pregnancies met criteria for inclusion, 11 of whom survived to discharge (survival rate 0.33; 95% CI 0.18, 0.52). More advanced gestational age was associated with increased likelihood of survival: 0 of 12 at 23 0/7 to 23 2/7 weeks, 4 of 10 at 23 3/7 to 23 4/7 weeks, and 7 of 11 at 23 5/7 to 23 6/7 weeks (P =.02). All 11 survivors developed RDS and chronic lung disease. One of 11 survivors had necrotizing enterocolitis, and 2 of 11 had severe retinopathy of prematurity. One survivor had periventricular leukomalacia on head ultrasonography, compared with 7 of the nonsurvivors who had head ultrasonography (P =.03). One survivor developed severe intraventricular hemorrhage (grade 3 or 4) compared with 8 of the 12 at-risk nonsurvivors who had head ultrasonography (P =.01).

CONCLUSION

About one third of infants delivered at 23 weeks' gestation survived to be discharged from neonatal intensive care. More advanced gestational age was associated with increased likelihood of survival. No neonates survived free of substantial morbidity.

Management of cervical cerclage and preterm premature rupture of the membranes: should the stitch be removed?

OBJECTIVE

Our aim was to determine whether retention of cerclage after preterm premature rupture of the membranes occurring before 34 completed weeks' gestation influences pregnancy outcome.

STUDY DESIGN

Singleton pregnancies with cerclage and premature rupture of the membranes between 24.0 and 34.9 weeks were reviewed. Women were excluded if they were first seen in labor, had chorioamnionitis, or were delivered within 48 hours. Control subjects consisted of women with premature rupture of the membranes without cerclage.

RESULTS

Eighty-one cases of cerclage with premature rupture of the membranes met criteria for inclusion: 30 women (37%) had their cerclage removed at presentation, and 51 (63%) retained the cerclage until delivery. Cases were similar in terms of gestational age at placement and gestational age at premature rupture of the membranes. There was no significant difference between the retained, removed, or control groups in terms of latency, gestational age at delivery, chorioamnionitis, or neonatal morbidity and mortality.

CONCLUSIONS

Retention of cervical cerclage after premature rupture of the membranes occurring before 34 completed weeks' gestation is associated with comparable clinical outcomes with respect to latency and perinatal outcome, when compared with removal of the cerclage.

Nutrition in adolescent pregnancy

Prevention of unintended adolescent pregnancy is a primary goal of the American Academy of Pediatrics and of many health providers. Nevertheless, many adolescents become pregnant every year in America. Pediatricians therefore should be aware of nutritional recommendations for pregnant adolescents to provide optimal care. The importance of nutrition during pregnancy is here reviewed from a pediatric perspective. Pregnancy, particularly during adolescence, is a time of extreme nutritional risk. The adolescents most likely to become pregnant are often those with inadequate nutritional status and unfavorable socio-economic background. There is increasing evidence of competition for nutrients between the growing pregnant adolescent and her fetus. Also, the prenatal environment has been implicated in the development of obesity, cardiovascular disease, and diabetes in both the mother and her offspring. Many adolescents have poor diet quality and poor knowledge of appropriate nutrition; these habits may not change during pregnancy. Current knowledge and recommendations regarding the intake of energy, calcium, and folate are discussed in detail.

Differences in TDx fetal lung maturity assay values between twin and singleton gestations

OBJECTIVE

The purpose of this study was to quantify differences in indexes of pulmonary maturity between singleton and twin gestations by means of the TDx fetal lung maturity assay.

STUDY DESIGN

We identified records of a total of 830 singleton and twin pregnancies not complicated by diabetes and delivered between 28 and 37 weeks' gestation from December 1994 through August 1995. Among these, 170 (20%) had TDx fetal lung maturity measurements performed within 72 hours of delivery. Linear regression was used to assess differences in TDx fetal lung maturity assay values between singleton gestations (n = 143 gestations) and twin gestations (n = 27 gestations) while controlling for potential confounding factors.

RESULTS

Twin gestations were no more likely than singleton gestations to undergo TDx fetal lung maturity screening (odds ratio, 1.3; 95% confidence interval, 0.8-2.2). Pregnancy complications and corticosteroid treatment were similar in the two groups. After 31 weeks' gestation the twin gestations had significantly higher TDx fetal lung maturity values. Linear regression with controls for gestational age indicated that twin gestations on average had a TDx fetal lung maturity value that was 22.0 mg/g (95% confidence interval, 9.8-34.6 mg/g) higher than that of gestational age-matched singleton gestations.

CONCLUSION

Beyond 31 weeks' gestation twin pregnancies appeared to have a TDx fetal lung maturity value that was 22 mg/g higher than that of singleton pregnancies. If the underlying incidences of respiratory distress syndrome are similar between twin and singleton gestations, then the potential exists for false-positive prediction of adequate lung maturity values among twin gestations.

Episiotomy, operative vaginal delivery, and significant perinatal trauma in nulliparous women

OBJECTIVES

The aim of this study was to determine whether choice of obstetric instrument at operative vaginal delivery is associated with any differences in the rate of significant perineal trauma and whether this rate is modified by the use of episiotomy.

STUDY DESIGN

The occurrence of significant perineal trauma among 323 consecutive operative vaginal deliveries was evaluated according to type of instrument used and performance of episiotomy. These findings were compared with spontaneous vaginal deliveries during the same period.

RESULTS

Among forceps deliveries the use of episiotomy was not associated with a difference in the occurrence of significant perineal trauma (55% vs 46%; relative risk, 1.2; 95% confidence interval, 0.8-1.9). Among vacuum extraction deliveries an increased rate of such trauma was noted when episiotomy was used (34.9% vs 9. 4%; relative risk, 3.7; 95% confidence interval, 1.2-11.2). There was no difference in the rate of significant perineal trauma according to type of forceps used. In a logistic regression analysis forceps delivery with or without episiotomy was associated with an increase of >10-fold in the rate of significant perineal trauma with respect to vacuum extraction deliveries without episiotomy.

CONCLUSIONS

Our data suggest that in forceps delivery neither the type of forceps nor episiotomy influences the risk of significant perineal trauma. When vacuum extraction delivery is performed, the use of episiotomy is associated with a higher risk of significant perineal trauma.

Epidural analgesia and third- or fourth-degree lacerations in nulliparas

OBJECTIVE

To determine if epidural analgesia is associated with differences in rates of severe perineal trauma during vaginal deliveries.

METHODS

We studied 1942 consecutive, low-risk, term, vaginal deliveries in nulliparas, including spontaneous and induced labors, at a single institution from December 1994 to August 1995. The rate of third- and fourth-degree lacerations was compared for women who had and did not have epidural analgesia for labor-pain relief. Statistical significance was determined using chi2. Logistic regression analyses were used to evaluate associations while controlling for possible confounding variables.

RESULTS

Overall rates of third- and fourth-degree lacerations were 10.8% (n = 210) and 3.4% (n = 63), respectively. Epidural analgesia was given to 1376 (70.9%) women. Among women who had epidurals, 16.1% (221 of 1376) had severe perineal lacerations compared with 9.7% (n = 55) of the 566 women who did not have epidurals (P < .001; odds ratio [OR] 1.8, 95% confidence interval [CI] 1.3, 2.4). When controlling for birth weight, use of oxytocin, and maternal age in logistic regression analysis, epidural remained a significant predictor of severe perineal injury (OR 1.4, 95% CI 1.0, 2.0). Epidural use is consistently associated with increased operative vaginal deliveries and consequent episiotomies, so we constructed a logistic regression model to evaluate whether the higher rates of those procedures were responsible for the effect of epidurals on severe perineal traumas. With operative vaginal delivery and episiotomy in the model, epidural was no longer an independent predictor of perineal injury (OR 0.9, 95% CI 0.6, 1.3).

CONCLUSION

Epidural analgesia is associated with an increase in the rate of severe perineal trauma because of the more frequent use of operative vaginal delivery and episiotomy.

Fertility therapy and the risk of very low birth weight

OBJECTIVE

To test the hypothesis of an association between maternal infertility therapy and the risk of very low birth weight (VLBW), defined as birth weight less than 1500 g, independent of the risk of multiple births, and to estimate the contribution of infertility therapy to the national incidence of VLBW.

METHODS

The National Maternal and Infant Health Survey conducted in 1988 was used to develop statistics describing outcomes among this birth cohort and to construct logistic regression models evaluating fertility therapy as an independent risk factor for VLBW.

RESULTS

An estimated 10.1% of live births and 18.2% of VLBW births nationally were associated with either maternal subfertility or infertility therapy (6.8% and 11.4%, respectively). The risk of VLBW among women concerned with subfertility (i.e., receiving diagnostic testing or advice on timing intercourse) was 1.4 (95% confidence interval [CI] 1.1, 1.9), whereas that for women undergoing therapeutic interventions (ie, ovarian stimulation, surgery, in vitro fertilization, or artificial insemination) was 2.6 (95% CI 2.1, 3.2). Accounting for effects of multiple gestation, maternal age, and a history of miscarriage, the odds ratios for the concerned and therapy groups were 1.5 (95% CI 1.1, 1.9) and 2.0 (95% CI 1.5, 2.5), respectively. Black women were less likely to use fertility therapy but more likely to experience a therapy-related VLBW.

CONCLUSION

Fertility therapy is associated with an important portion of all VLBW and with an elevated risk of VLBW, related only in part to an increased risk of multiple gestations. Women expressing concern about subfertility but not receiving therapy are also at increased risk of VLBW, suggesting that a history of infertility may mediate part of the risk associated with fertility therapy.