Perinatal outcome in growth-restricted fetuses: do hypertensive and normotensive pregnancies differ?

Association of Maternal Preeclampsia With Infant Risk of Premature Birth and Retinopathy of Prematurity

Importance

Studies report conflicting associations between preeclampsia and retinopathy of prematurity (ROP). This study provides explanations for the discrepancies to clarify the relationship between preeclampsia and ROP.

Objective

To evaluate the association of maternal preeclampsia and risk of ROP among infants in an unrestricted birth cohort and a restricted subcohort of preterm, very low birth weight (P-VLBW) infants.

Design, Setting, and Participants

A retrospective review of 290 992 live births within the Intermountain Healthcare System in Utah from January 1, 2001, through December 31, 2010, was performed. Generalized estimating equations for logistic regressions with covariate adjustment were applied to relate ROP to preeclampsia among the full cohort and in a subcohort of P-VLBW infants born at younger than 31 weeks' gestation and weighing less than 1500 g.

Main Outcomes and Measures

The occurrence of ROP was related to maternal preeclampsia in the full cohort and in a subcohort of P-VLBW infants.

Results

In the full cohort, 51% of the infants were male and the mean (SD) gestational age was 38.38 (1.87) weeks. In the P-VLBW cohort, 55% were male and the mean (SD) gestational age was 26.87 (2.40) weeks. In the full cohort, preeclampsia was associated with an increased risk of all ROP (adjusted odds ratio [aOR], 2.46; 95% CI, 2.17-2.79; P < .001), severe ROP (aOR, 5.21; 95% CI, 3.44-7.91; P < .001), infant death (aOR, 1.66; 95% CI, 1.16-2.38; P = .006), and giving birth to a P-VLBW infant (aOR, 7.74; 95% CI, 6.92-8.67; P < .001). In the P-VLBW subcohort, preeclampsia was inversely associated with the development of all ROP (aOR, 0.79; 95% CI, 0.68-0.92; P = .003), severe ROP (aOR, 0.62; 95% CI, 0.36-1.06; P = .08), and infant death (aOR, 0.19; 95% CI, 0.11-0.32; P < .001).

Conclusions and Relevance

Preeclampsia was associated with an increased risk of developing ROP among an unrestricted cohort but with a reduced risk of ROP among a restricted subcohort of P-VLBW infants. Although the conflicting associations in the full and P-VLBW cohorts may reflect true differences, the association of a reduced risk of ROP among the P-VLBW subcohort also may reflect biases from restricting the cohort to prematurity, because prematurity is an outcome of preeclampsia.

Fetal growth restriction and risk of cerebral palsy in singletons born after at least 35 weeks' gestation

OBJECTIVE

The objective of the study was to improve the understanding of etiological paths to cerebral palsy (CP) that include fetal growth restriction by examining factors associated with growth restriction that modify CP risk.

STUDY DESIGN

In a total population of singletons born at or after 35 weeks, there were 493 children with CP and 508 matched controls for whom appropriateness of fetal growth could be estimated. Fetal growth was considered markedly restricted if birthweight was more than 2 SD below optimal for gender, gestation, maternal height, and parity. We examined maternal blood pressure in pregnancy, smoking, birth asphyxia, and major birth defects recognized by age 6 years as potential modifiers of CP risk in growth-restricted births.

RESULTS

More than 80% of term and late preterm markedly growth-restricted singletons were born following a normotensive pregnancy and were at statistically significantly increased risk of CP (odds ratio, 4.81; 95% confidence interval, 2.7-8.5), whereas growth-restricted births following a hypertensive pregnancy were not. Neither a clinical diagnosis of birth asphyxia nor potentially asphyxiating birth events occurred more frequently among growth-restricted than among appropriately grown infants with CP. Major birth defects, particularly cerebral defects, occurred in an increasing proportion of CP with increasing growth deficit. The factor most predictive of CP in growth-restricted singletons was a major birth defect, present in 53% of markedly growth-restricted neonates with later CP. Defects observed in CP were similar whether growth restricted or not, except for an excess of isolated congenital microcephaly in those born growth restricted. The highest observed CP risk was in infants with both growth restriction and a major birth defect (8.9% of total CP in this gestational age group, 0.4% of controls: odds ratio, 30.9; 95% confidence interval, 7.0-136).

CONCLUSION

The risk of CP was increased in antenatally growth-restricted singletons born at or near term to normotensive mothers. In growth-restricted singletons, a major birth defect was the dominant predictor, associated with a 30-fold increase in odds of CP. Identification of birth defects in the growth-restricted fetus or neonate may provide significant prognostic information.

Risk of fetal death with preeclampsia

OBJECTIVE

To estimate gestational age-specific risks of fetal death in pregnancies complicated by preeclampsia.

METHODS

Population-based cohort study comprising all singleton births (N=554,333) without preexisting chronic hypertension recorded in the Norwegian Medical Birth Registry from 1999 to 2008. Additional data come from a subset of preeclamptic pregnancies enrolled in the Norwegian Mother and Child Cohort Study with available medical records (n=3,037). The risk of fetal death, expressed per 1,000 fetuses exposed to preeclampsia, was calculated using a life table approach.

RESULTS

Preeclampsia was recorded in 3.8% (n=21,020) of all pregnancies. Risk of stillbirth was 3.6 per 1,000 overall and 5.2 per 1,000 among pregnancies with preeclampsia (relative risk 1.45, 95% confidence interval [CI] 1.20-1.76). However, relative risk of stillbirth was markedly elevated with preeclampsia in early pregnancy. At 26 weeks of gestation, there were 11.6 stillbirths per 1,000 pregnancies with preeclampsia compared with 0.1 stillbirths per 1,000 pregnancies without (relative risk 86, 95% CI 46-142). Fetal risk with preeclampsia declined as pregnancy advanced, but at 34 weeks of gestation remained more than sevenfold higher than pregnancies without preeclampsia.

CONCLUSION

For clinical purposes, the fetal risk of death associated with preeclampsia begins when preeclampsia becomes clinically apparent. Using a method that takes into account the clinical diagnosis of preeclampsia and the population of fetuses at risk, we find a remarkably high relative risk of fetal death among pregnancies diagnosed with preeclampsia in the preterm period.

LEVEL OF EVIDENCE

II.

Parenteral nutrition associated cholestasis is earlier, more prolonged and severe in small for gestational age compared with appropriate for gestational age very low birth weight infants

PURPOSE

We hypothesized that parenteral nutrition associated cholestasis (PNAC) would be more severe in small for gestational age (SGA) compared with appropriate for gestational age (AGA) very low birth weight (VLBW) infants.

MATERIALS AND METHODS

Sixty-one VLBW infants were diagnosed as PNAC with exposure to parenteral nutrition with elevation of direct bilirubin≥2 mg/dL for ≥14 days. Twenty-one SGA infants and 40 AGA infants matched for gestation were compared.

RESULTS

Compared with AGA infants, PNAC in SGA infants was diagnosed earlier (25±7 days vs. 35±14 days, p=0.002) and persisted longer (62±36 days vs. 46±27 days, p=0.048). Severe PNAC, defined as persistent elevation of direct bilirubin≥4 mg/dL for more than 1 month with elevation of liver enzymes, was more frequent in SGA than in AGA infants (61% vs. 35%, p=0.018). The serum total bilirubin and direct bilirubin levels during the 13 weeks of life were significantly different in SGA compared with AGA infants. SGA infants had more frequent (76% vs. 50%, p=0.046), and persistent elevation of alanine aminotransferase.

CONCLUSION

The clinical course of PNAC is more persistent and severe in SGA infants. Careful monitoring and treatment are required for SGA infants.

Does advanced maternal age confer a survival advantage to infants born at early gestation?

BACKGROUND

Recent studies have shown that older mothers who deliver at preterm gestation have lower neonatal mortality rates compared with younger mothers who deliver at preterm gestation. We examined the effect of maternal age on gestational age-specific perinatal mortality.

METHODS

We compared fetal, neonatal and perinatal mortality rates among singleton births in the United States, 2003-2005, to mothers aged ≥35 versus 20-29 years. The analysis was stratified by gestational age and perinatal mortality rates were contrasted by maternal age at earlier (22-33 weeks) and later gestation (≥34 weeks). Gestational age-specific perinatal mortality rates were calculated using the traditional perinatal formulation (deaths among births at any gestation divided by total births at that gestation) and also the fetuses-at-risk model (deaths among births at any gestation divided by fetuses-at-risk of death at that gestation).Logistic regression was used to estimate adjusted odds ratios (AOR) for perinatal death.

RESULTS

Under the traditional approach, fetal death rates at 22-33 weeks were non-significantly lower among older mothers (AOR 0.97, 95% confidence interval [CI] 0.91-1.03), while rates were significantly higher among older mothers at ≥34 weeks (AOR 1.66, 95% CI 1.56-1.76). Neonatal death rates were significantly lower among older compared with younger mothers at 22-33 weeks (AOR=0.93, 95% CI 0.88-0.98) but higher at ≥34 weeks (AOR 1.26, 95% CI 1.21-1.31). Under the fetuses-at-risk model, both rates were higher among older vs younger mothers at early gestation (AOR for fetal and neonatal mortality 1.35, 95% CI 1.27-1.43 and 1.31, 95% CI 1.24-1.38, respectively) and late gestation (AOR for fetal and neonatal mortality 1.66, 95% CI 1.56-1.76) and 1.21, 95% CI 1.14-1.29, respectively).

CONCLUSIONS

Although the traditional prognostic perspective on the risk of perinatal death among older versus younger mothers varies by gestational age at birth, the causal fetuses-at-risk model reveals a consistently elevated risk of perinatal death at all gestational ages among older mothers.

Educational inequalities in preterm and term small-for-gestational-age birth over time

PURPOSE

Time trends in educational inequalities in small-for-gestational-age (SGA) birth are important to evaluate for policy, especially at preterm gestational ages when morbidity and mortality are typically greater. We evaluated educational inequalities in preterm and term SGA birth over time, accounting for potential bias at preterm gestational ages.

METHODS

Data included 2,204,056 singleton live births from 25 to 43 gestational weeks, 1981 to 2007. We estimated prevalence ratios (PR) and percent prevalence differences (PPD) of preterm and term SGA birth for a continuous education score, accounting for maternal characteristics. Sensitivity analyses included correction for misclassification of preterm SGA status, and use of fetuses-at-risk denominators in regression models.

RESULTS

Although prevalence of SGA birth decreased over time, relative educational inequalities (PRs) persisted for preterm and term cases. PPDs decreased slightly, but more for term than preterm SGA birth. Sensitivity analyses indicated that PRs for education were stronger for preterm than term SGA birth. PPDs were larger for term SGA birth in the first period, but greater for preterm SGA birth in the last period.

CONCLUSIONS

Relative educational inequalities in SGA birth persisted over time. The difference in prevalence between the least and most educated mothers is currently greater for preterm than for term SGA birth.

Impact of fetal growth restriction on mortality and morbidity in a very preterm birth cohort

OBJECTIVE

To assess the impact of being small for gestational age (SGA) on very preterm mortality and morbidity rates by using different birthweight percentile thresholds and whether these effects differ by the cause of the preterm birth.

STUDY DESIGN

The study included singletons and twins alive at onset of labor between 24 and 31 weeks of gestation without congenital anomalies from the Models of Organising Access to Intensive Care for very preterm births very preterm cohort in 10 European regions in 2003 (n = 4525). Outcomes were mortality, intraventricular hemorrhage grade III and IV, cystic periventricular leukomalacia, and bronchopulmonary dysplasia (BPD). Birthweight percentiles in 6 classes were analyzed by pregnancy complication.

RESULTS

The mortality rate was higher for infants with birthweights <25th percentile when compared with the 50th to 74th percentile (adjusted odds ratio, 3.98 [95% CI, 2.79-5.67] for <10th; adjusted odds ratio, 2.15 [95% CI, 1.54-3.00] for 10th-24th). BPD declined continuously with increasing birthweight. There was no association for periventricular leukomalacia or intraventricular hemorrhage. Seventy-five percent of infants with birthweights <10th percentile were from pregnancies complicated by hypertension or indicated deliveries associated with growth restriction. However, stratifying for pregnancy complications yielded similar risk patterns.

CONCLUSIONS

A 25th percentile cutoff point was a means of identifying infants at higher risk of death and a continuous measure better described risks of BPD. Lower birthweights were associated with poor outcomes regardless of pregnancy complications.

Subsequent pregnancy outcome after first pregnancy with normotensive early-onset intrauterine growth restriction at <34 weeks of gestation

OBJECTIVE

The aim of this study was to evaluate maternal and fetal outcome of the subsequent pregnancy of primiparous women with a history of early-onset intrauterine growth restriction (IUGR), prompting delivery before 34 weeks of gestation, without concomitant maternal hypertensive disease.

DESIGN

Retrospective cohort study.

SETTING

Tertiary center in the Netherlands.

POPULATION

Women with a normotensive first pregnancy complicated by early-onset severe IUGR, prompting delivery before 34 weeks of gestation.

METHODS

Reproductive follow-up data were recorded for 22 women with a normotensive first pregnancy complicated by early-onset severe IUGR before 34 weeks, referred to the University Medical Centre Utrecht, the Netherlands, between 1993 and 2005.

MAIN OUTCOME MEASURES

Main outcome measures were recurrent IUGR, perinatal mortality, preterm delivery, preeclampsia (PE), pregnancy-induced hypertension, and other major obstetric complications, for example placental abruption.

RESULTS

Mean gestational age at delivery was 29.4 weeks for the index pregnancy compared to 36.4 weeks for the next pregnancy. IUGR recurred in six pregnancies (27.3%). Four subsequent pregnancies were complicated by hypertensive disorders. Perinatal mortality was 72.7% in the index pregnancy, compared to 13.6% in the second pregnancy. Overall, 11 women (54.5%) had an uneventful pregnancy.

CONCLUSION

Women with first pregnancy early-onset IUGR, without concomitant maternal hypertensive disease, frequently develop severe perinatal complications in their subsequent pregnancy.

Does pre-eclampsia influence fetal cardiovascular function in early-onset intrauterine growth restriction?

OBJECTIVES

Increasing evidence shows that intrauterine growth restriction (IUGR) is associated with fetal cardiac dysfunction. Most studies group IUGR with and without pre-eclampsia (PE) altogether. Our objective was to evaluate whether the association with PE has any impact on cardiac function in IUGR fetuses

METHODS

Thirty-one normotensive IUGR cases and 31 IUGR cases with pre-eclampsia (PE + IUGR) below 34 weeks of gestation were included. IUGR was defined as a birth weight below the 10(th) centile together with an umbilical artery pulsatility index above 2 SD. Fetal cardiac function was assessed by measuring ductus venosus pulsatility index, modified myocardial performance index, aortic isthmus blood flow, E/A ratios and cardiac output. The presence of fetal cardiac dysfunction was also assessed by measuring cord blood B-type natriuretic peptide (BNP) levels collected at birth. Echocardiographic data were compared with those in 80 term appropriate-for-gestational age (AGA) fetuses from normotensive mothers. Cord blood BNP levels were compared with those in 40 AGA cases that delivered preterm.

RESULTS

All IUGR cases (with or without PE) showed echocardiographic and biochemical signs of cardiac dysfunction compared with AGA cases. However, no differences were observed between IUGR and PE + IUGR cases either in echocardiographic or in biochemical parameters. IUGR cases with or without PE had similar perinatal results.

CONCLUSIONS

IUGR fetuses showed echocardiographic and biochemical signs of cardiac dysfunction. Pre-eclampsia per se does not influence cardiac function in IUGR fetuses.

Newborn weight charts underestimate the incidence of low birthweight in preterm infants

OBJECTIVE

The objective of the study was to compare sonographic fetal weight estimates with newborn weight charts and analyze the predictive accuracy of the ponderal index (PI) in preterm infants.

STUDY DESIGN

We generated sonographic reference curves for fetal weight and PI estimates from a database of fetal biometric records from 12,589 term deliveries. We then plotted sonographic and newborn weight and PI of 2406 preterm newborns on these curves and compared them with published newborn weight charts.

RESULTS

The third centiles of sonographic and newborn weights diverged markedly between 25 and 36 weeks of gestation and by more than 400 g at 32-33 weeks. In contrast, sonographic and newborn PI values were similar despite uncertainties as to fetal length.

CONCLUSION

We suggest using sonographic reference fetal weights to screen preterm newborns for low birthweight. Uncertainties in fetal length threaten the reliability of the PI.

Conventional birth weight standards obscure fetal growth restriction in preterm infants

BACKGROUND AND OBJECTIVE

It has been suggested that fetal growth restriction (FGR) is associated with fetal maturation so that, compared with appropriately grown preterm infants, mortality and some neonatal morbidities may be reduced. The evidence for this is conflicting, and severe FGR has been shown to be harmful. In addition excessive growth has also been shown to be associated with poorer outcomes. As preterm infants are often also growth restricted, centiles for birth weights are distorted and may conceal the degree of growth restriction in a given infant. This study investigated whether using estimated fetal weights (EFW) might reveal the effects of hidden FGR.

POPULATION AND METHODS

Using a 25-year database of preterm admissions to a single neonatal unit the ORs for mortality and neonatal morbidities for z scores for birth weight above and below the mean were computed and compared with those computed for z scores for EFW.

RESULTS

In 7898 infants born at less than 35 weeks' gestation, the OR for mortality was lowest for birth weights between 1 SD and 3 SD above the mean, but was lowest for EFW between -2 SD and 0 SD below the mean. For periventricular haemorrhage, increasing FGR below the mean reduced the OR with both birth weight and EFW. Apparent reductions in OR for septicaemia, chronic lung disease, persistent ductus arteriosus and necrotising enterocolitis with birth weights of >1 SD above the mean were not seen with EFW. FGR of >-3 SD was associated with increased OR for necrotising enterocolitis with both birth weight and EFW.

CONCLUSION

Using fetal growth rather than birth weight standards gives a better indication of the incidence and role of FGR in neonatal disease.

Hydramnios and small for gestational age are independent risk factors for neonatal mortality and maternal morbidity

OBJECTIVE

The objective was to evaluate the contribution of hydramnios and small for gestational age (SGA) as a combined pathology to maternal and neonatal morbidity and mortality.

METHODS

The study population consisted of 192 SGA neonates with hydramnios, 5,515 SGA neonates with a normal amount of amniotic fluids, 3,714 appropriate for gestational age (AGA) neonates with polyhydramnios and 83,763 AGA neonates with a normal amount of amniotic fluid. A cross-sectional population based study was designed between the four study groups. Multiple logistic regression analysis was used to assess the contribution of these abnormalities and different risk factors to maternal and perinatal complications.

RESULTS

The combination of hydramnios/SGA was found to be an independent risk factor for perinatal mortality (OR 20.55; CI 12.6-33.4). Congenital anomalies, prolapse of cord, hydramnios, SGA and grand multiparity were also independent risk factors for perinatal mortality. Independent risk factors for neonatal complications were prolapse of umbilical cord (OR 4.13; 95% CI 1.48-11.5), hydramnios/SGA (OR 2.72; 95% CI 1.81-4.07), chronic hypertension (OR 2.45; 95% CI 1.02-5.9), congenital malformations (OR 1.93; 95% CI 1.14-3.24) and SGA (OR 1.47; 95% CI 1.07-2). Significant independent risk factors for medical interventions during labor were fetal distress (OR 198.46; 95% CI 47.27-825.27), GDM Class B-R (OR 21.22; 95% CI 2.34-192.25), GDM class A (OR 4.64; 95% CI 2.62-8.21), severe pregnancy-induced hypertension (PIH; OR 7.74; 95% CI 2.35-25.42), hydramnios (OR 1.95; 95% CI 1.3-2.91), hydramnios/SGA (OR 1.84; 95% CI 1.12-3.02) and malpresentation (OR 1.56; 95% CI 1.32-1.84).

CONCLUSION

The combination of hydramnios and SGA is an independent risk factor for perinatal mortality and maternal complications. We suggest that the growth restriction of these fetuses is responsible for the neonatal complications, while the hydramnios contributes mainly to maternal complications.

Prenatal and perinatal determinants of neonatal seizures occurring in the first week of life

To evaluate prenatal and perinatal risk factors for early neonatal seizures, we conducted a case-control study including 100 newborns with neonatal seizures in the first week of life and 204 controls randomly selected from a list of healthy newborns born in the same hospital during the study period. Generalized tonic seizures were the most common seizures observed (29%), although the majority of newborns (71%) experienced more than one type of seizure. The most frequent presumed etiology of neonatal seizures was hypoxic-ischemic encephalopathy (30%). A history of epilepsy in first-degree relatives was found only for cases. Neonatal seizures were found to be associated with maternal disease in the 2 years before pregnancy, mother's weight gain > 14 kg during pregnancy, placental pathology, preeclampsia, low birthweight, low gestational age, and jaundice in the first 3 days of life. The need for cardiopulmonary resuscitation was found only for cases (37%). The causal pathways for neonatal seizures often begin before birth, and some of the factors identified may be preventable.

MOS HIP: McMaster outcome study of hypertension in pregnancy

BACKGROUND

The offspring of women with hypertension during pregnancy are at increased risk of low birthweight, preterm birth, diseases of prematurity and death. The risk of developing these outcomes among women with either preeclampsia or chronic hypertension, relative to those with gestational hypertension, is not known.

STUDY DESIGN

Prospective cohort study.

PARTICIPANTS

A total of 1948 singleton women seen at a large tertiary care obstetrical center, whose blood pressure was greater than 140/90 mm Hg during pregnancy. The four types of hypertension were strictly defined: 864 women (44.4%) had gestational hypertension, 459 (23.6%) isolated chronic hypertension, 501 (25.7%) isolated preeclampsia, and 124 (6.4%) chronic hypertension with superimposed preeclampsia.

OUTCOME MEASURES

The primary outcome of the study was a composite of the diseases of prematurity, need for assisted ventilation for greater than 1 day, or perinatal death. The secondary outcomes were each of those included in the primary endpoint, as well as admission to the neonatal ICU, small for gestational age (SGA) birthweight and preterm birth. We controlled for the effects of other maternal risk factors, such as age, parity, history of preterm delivery, cigarette smoking, pre-pregnancy weight, diabetes mellitus (DM), renal dysfunction, and current use of an antihypertensive agent or prednisone.

RESULTS

For the primary composite outcome, compared to the offspring of women with gestational hypertension, the adjusted odds ratio was 1.9 (95% confidence interval 1.2 to 3.0) in the preeclamptic group and 2.0 (95% confidence interval 1.0 to 4.0) for those with chronic hypertension plus superimposed preeclampsia. Those with preeclampsia were at increased risk for small for gestational age birthweight (odds ratio 2.2, 95% confidence interval 1.5 to 3.1), as were the offspring of mothers who had chronic hypertension with superimposed preeclampsia (odds ratio 2.1, 95% confidence interval 1.2 to 3.8). Similarly, the rate of preterm birth before 32 weeks was highest among the infants of both preeclamptic mothers (28.5%; odds ratio 4.7, 95% confidence interval 2.9 to 7.6) and those with chronic hypertension and preeclampsia (30.5%; odds ratio 3.5, 95% confidence interval 1.8 to 6.7). The perinatal mortality rate was highest in the group of women with chronic hypertension plus preeclampsia (9.2%; odds ratio 3.2, 95% confidence interval 1.2 to 9.1). Other significant risk factors for the primary composite outcome included previous preterm delivery (odds ratio 2.7, 95% confidence interval 1.4 to 5.2), smoking (odds ratio 1.8, 95% confidence interval 1.1 to 3.0) and use of an antihypertensive agent during pregnancy (odds ratio 1.8, 95% confidence interval 1.2 to 2.7). Prednisone use was strongly associated with risk for perinatal death (odds ratio 4.9, 95% confidence interval 1.4 to 17.1).

CONCLUSIONS

Relative to women with isolated gestational hypertension, those who develop preeclampsia, either with or without underlying chronic hypertension, experience worse perinatal outcomes. A history of previous preterm delivery and maternal smoking increase the rate preterm birth and major perinatal disease. Antihypertensive and prednisone therapy may be important risk factors for adverse perinatal events, but further research is needed to confirm these findings.

Consequences of fetal growth restriction

An increasing number of diseases in child and adult life are now thought to have their origins in the fetal period. Central to this predisposition is restriction of fetal growth. During the period reviewed in this article, the associations between adult hypertension and low birthweight were confirmed, and numerous studies have investigated possible mechanisms by which the metabolism of an individual may be programmed by an adverse intrauterine environment. The consequences in adult life of intrauterine undernutrition now highlight prenatal care as one of the most crucial issues in medicine and challenge many aspects of current obstetric decision-making. Research targeting fetal growth and development can be expected to result in improved health at all ages.