Advanced maternal age and the outcomes of preterm neonates: a social paradox?

Trends in Retinopathy of Prematurity Among Preterm Infants in California, 2012 to 2021

Importance

The incidence of retinopathy of prematurity (ROP) has been increasing in the US since 2003. Understanding the progression of and racial disparities in ROP incidence in California can provide a contrasting perspective that may guide future research and practice in the management and prevention of ROP.

Objective

To describe how the screening and incidence of ROP among very preterm infants in California changed from January 1, 2012, to December 31, 2021.

Design, Setting, and Participants

This study used a cohort of very preterm infants (defined as infants born prior to 32 weeks' gestational age or weighing less than 1500 g) admitted to 60 neonatal intensive care units across California from January 1, 2012, to December 31, 2021. Among this cohort, several factors were examined, including (1) the clinical and sociodemographic covariates of the population with and without ROP, (2) trends in screening for ROP, and (3) the incidence of ROP in total and by race and ethnicity. Data analysis was performed in April 2024.

Exposures

Race and ethnicity and other birthing parental and infant descriptive characteristics.

Main Outcomes and Measures

Incidence rates of ROP and severe ROP. The primary measures were rates of ROP screening and incidence rates of ROP and severe ROP. Time trends in the risk of ROP and severe ROP were estimated using robust Poisson regression models.

Results

In this cohort of 39 269 very preterm infants (<32 weeks' gestational age) eligible for ROP screening, the mean (SD) infant gestational age was 28.6 (2.6) weeks. The mean (SD) birth weight was 1075 (274) g, and 48.6% of infants were female. The birthing parents of the population were 12.6% Asian, 13.3% Black, 44.9% Hispanic White or Hispanic other race, 0.7% Native American/Alaskan, 24.7% non-Hispanic White, and 1.0% Pacific Islander. From January 1, 2012, to December 31, 2021, in California, ROP screening rates remained steady at 95% or greater for eligible infants less than 30 weeks of gestational age for all race and ethnic subgroups. In this study cohort among all very preterm infants (<32 weeks' gestational age), the incidence of ROP decreased from 31% in 2012 to 29% in 2021. Incidence rates of ROP among Asian and Hispanic individuals decreased the most quickly compared to other racial and ethnic groups, narrowing disparities.

Conclusions and Relevance

In this cohort study, in contrast to increasing national trends, the total incidence of and racial and ethnic disparities in ROP incidence remained steady or decreased from 2012 to 2021 in California.

Impact of advanced maternal age on neonatal morbidity: a systematic review

OBJECTIVE

This systematic review aimed to understand the impact of advanced maternal age (AMA) on the neonatal morbidity, based on the available scientific evidence.

METHODS

A systematic search was conducted on 22 November 2021, using the PubMed and Scopus databases to identify studies that compared the morbidity of neonates delivered to AMA mothers with that of neonates delivered to non-AMA mothers.

RESULTS

Sixteen studies that evaluated the effect of AMA on the neonatal morbidity were included in this review. Nine of these studies found some association between AMA and increased neonatal morbidity (with two of them only reporting an increase in asymptomatic hypoglycemia, and one only reporting an association in twins), six found no association between AMA and neonatal morbidity and one study found a decrease in morbidity in preterm neonates. The studies that found an increase in overall neonatal morbidity with AMA considered older ages for the definition of AMA, particularly ≥40 and ≥45 years.

CONCLUSION

The current evidence seems to support a lack of association between AMA and the neonatal morbidity of the delivered neonates. However, more studies focusing on the neonatal outcomes of AMA pregnancies are needed to better understand this topic.

Effect of maternal age on neonatal outcomes in very low birth weight singleton infants: a population-based study

BACKGROUND

Little is known on the impact of maternal age (MA) on very low birth weight (VLBW) infants' outcomes. We tested the hypothesis that at both ends of MA there are increased adverse neonatal outcomes in VLBW infants.

METHODS

We used the Israel National Neonatal Network VLBW (≤1500 g) database. Maternal age was stratified as: <20, 20-24, 25-34 (reference group), 35-39 and ≥40 years. Statistical analyses were univariate and multivariable logistic regression analysis.

RESULTS

After adjustment, the infant outcomes of older mothers were similar to those of the reference group for mortality, RDS, severe ROP, NEC and sepsis. Mothers < 20 and 20-24 years old had higher odds of IVH grades 3-4 (OR 1.45, 95% CI 1.09-1.93 and OR 1.26, 95% CI 1.10-1.45, respectively), and BPD (OR 1.55, 95% CI 1.13-2.13 and OR 1.40, 95% CI 1.22-1.62, respectively). There were higher odds for PVL in infants of <20 year-old mothers (OR 1.83, 95% CI 1.26-2.65) and in infants of 35-39 year-old mothers (OR 1.38, 95% CI 1.12-1.69). Poor composite outcomes were significantly higher in the youngest maternal age categories (<20-year-old mothers (OR 1.63, 95% CI 1.28-2.08), and 20-24-year-old (OR 1.28, 95% CI 1.15-1.43).

CONCLUSIONS

Neonatal outcomes differ in relation to maternal age among very low birth weight newborns, with adverse outcomes more predominant in infants of younger mothers.

Risk prediction of bronchopulmonary dysplasia in preterm infants by the nomogram model

Backgrounds and Aims

Bronchopulmonary dysplasia (BPD) has serious immediate and long-term sequelae as well as morbidity and mortality. The objective of this study is to develop a predictive model of BPD for premature infants using clinical maternal and neonatal parameters.

Methods

This single-center retrospective study enrolled 237 cases of premature infants with gestational age less than 32 weeks. The research collected demographic, clinical and laboratory parameters. Univariate logistic regression analysis was carried out to screen the potential risk factors of BPD. Multivariate and LASSO logistic regression analysis was performed to further select variables for the establishment of nomogram models. The discrimination of the model was assessed by C-index. The Hosmer-Lemeshow test was used to assess the calibration of the model.

Results

Multivariate analysis identified maternal age, delivery option, neonatal weight and age, invasive ventilation, and hemoglobin as risk predictors. LASSO analysis selected delivery option, neonatal weight and age, invasive ventilation, hemoglobin and albumin as the risk predictors. Both multivariate (AUC = 0.9051; HL P = 0.6920; C-index = 0.910) and LASSO (AUC = 0.8935; HL P = 0.7796; C-index = 0.899) - based nomograms exhibited ideal discrimination and calibration as confirmed by validation dataset.

Conclusions

The probability of BPD in a premature infant could be effectively predicted by the nomogram model based on the clinical maternal and neonatal parameters. However, the model required external validation using larger samples from multiple medical centers.

The effect of advanced maternal age on perinatal outcomes in nulliparous pregnancies

OBJECTIVES

In the current study, we aimed to evaluate the effect of advanced maternal age on perinatal outcomes in nulliparous singleton pregnancy.

METHODS

The perinatal outcome data of 11,366 patients who gave birth between 2015 and 2020 were evaluated retrospectively. Patients were subgrouped according to their age as control group (C) (20-29 years), late advanced maternal age group (30-34 years), advanced maternal age group (35-39 years), and very advanced maternal age group (≥40 years). Multinomial logistic regression analyses were performed to test the possible independent role of maternal age as a risk factor for adverse pregnancy outcomes.

RESULTS

Statistically significant difference was observed between the control group and the other groups in terms of preterm delivery, preeclampsia, gestational diabetes mellitus (GDM), small gestational age (SGA), large gestational age (LGA), premature rupture of membranes (PROM), high birth weight (HBW), and perinatal mortality rates (p<0.05). An increased risk of the need for neonatal intensive care unit (NICU) and perinatal mortality was observed in groups over 35 years old.

CONCLUSIONS

Age poses a risk in terms of preterm delivery, preeclampsia, LGA, GDM, and HBW in the groups over 30 years of maternal age. The rates of PROM, NICU, and perinatal mortality increase in addition to those perinatal results in the groups above 35 years of maternal age.

Impact of maternal age on neonatal outcomes among very preterm infants admitted to Chinese neonatal intensive care units: a multi-center cohort study

BACKGROUND

The percentage of advanced maternal age (aged over 35 years) mothers has been rising across the world, the evidence of maternal age on neonatal outcomes from low- and middle-income countries is scarce. Our objective was to evaluate the effect of maternal age on mortality and major morbidity among very preterm infants admitted to Chinese neonatal intensive care units.

METHODS

Data from a retrospective multi-center cohort of all complete care very preterm infants admitted to 57 neonatal intensive care units that participated in the Chinese Neonatal Network from January 1st to December 31st, 2019 were analyzed. Neonatal outcomes including mortality or any major morbidity, defined as necrotizing enterocolitis stage 2 or 3, moderate & severe bronchopulmonary dysplasia, severe intraventricular hemorrhage, cystic periventricular leukomalacia, severe retinopathy of prematurity, or sepsis. A multiple logistic regression model was constructed to analyze the independent association between maternal age and neonatal outcome.

RESULTS

Among 7,698 eligible newborns, 80.5% of very preterm infants were born to mothers between the ages of 21 and 35 years, with 18.0% born to mothers >35 years and 1.5% born to mothers <21 years. Higher rates of maternal hypertension, maternal diabetes, cesarean deliveries, antenatal steroid usage were noted as maternal age increased. The proportion of prenatal care, cesarean section, antenatal steroid usage and inborn for very preterm infants born to mothers <21 years was lower than those of mothers of other ages. Compared to the ages of 21-35 years group, the odds of severe intraventricular hemorrhage (adjusted odd ratio: 2.00, 95% CI: 1.08-3.71) was significantly higher in the ages of 15-20 years group. Increasing maternal age was associated with higher rates of small for gestational age and lower birth weight of very preterm infants, but no correlation between advanced maternal age and very preterm infants mortality or major morbidity.

CONCLUSIONS

Among very preterm infants, increasing maternal age was associated with higher rates of small for gestational age but not neonatal mortality or major morbidity. Young maternal age may increase the risk of severe intraventricular hemorrhage of very preterm infants.

Short-term outcomes of very-low-birth-weight infants born to mothers of advanced and very advanced maternal age

OBJECTIVE

To evaluate whether advanced maternal age (35-39 years, AMA)/very advanced maternal age (≥40 years, VAMA) impacts neonatal outcomes of very-low-birth-weight (VLBW) infants.

METHODS

Data of VLBW infants admitted to our unit were reviewed. Demographic findings and neonatal outcomes were compared among maternal age [(<35 years, not advanced maternal age, n = 329), AMA (n = 209), and VAMA (n = 43)] groups. Univariate and multivariate analyses were performed to identify the associated risk factors for neonatal outcomes.

RESULT

Mortality and overall morbidities showed no significant intergroup differences, except for massive pulmonary hemorrhage (MPH). Multivariate analysis revealed that AMA/VAMA was not significantly associated with MPH development, while ≥ two doses of surfactant administration was. Higher gestational age and antenatal corticosteroid administration were protective.

CONCLUSION

AMA/VAMA is not associated with neonatal mortality and morbidities. Since the proportion of AMA/VAMA mothers is expected to increase, perinatal medicine practitioners should focus on approaches before and immediately after birth of such infants.

Increased Risk for Respiratory Complications in Male Extremely Preterm Infants: A Propensity Score Matching Study

BACKGROUND

Many factors can affect the clinical outcome of extremely premature infants (EPIs), but the effect of sex is paradoxical. This study used propensity score matching to adjust baseline information to reassess the clinical outcome of EPIs based on sex.

METHODS

A retrospective analysis was performed on EPIs admitted in the Department of Neonatology of the Third Affiliated Hospital of Guangzhou Medical University from 2011 to 2020. A propensity score matching (PSM) analysis was used to adjust the confounding factors including gestational age, birth weight, 1-minute Apgar score ≤ 3, withholding or withdrawing life-sustaining treatment(WWLST), mechanical ventilation, duration of mechanical ventilation, the mother with advanced age (≥35 years old), complete-course antenatal steroid therapy and hypertensive disorders of pregnancy. The survival rate at discharge and the incidence of major complications were evaluated between the male and female groups.

RESULTS

A total of 439 EPIs were included, and 240 (54.7%) infants were males. After matching the nine confounding factors, 148 pairs of infants were finally enrolled. There was no significant difference in the survival rate at discharge, as well as the mortality of activating treatment or WWLST between the two groups (all P>0.05). However, the incidence of respiratory distress syndrome, bronchopulmonary dysplasia (BPD), and moderate to severe BPD in the male group was significantly increased (all P<0.01), especially at birth weight between 750 and 999 grams.

CONCLUSIONS

The male EPIs have a higher risk of respiratory complications than females, particularly at 750 to 999 grams of birth weight.

Bias in comparisons of mortality among very preterm births: A cohort study

BACKGROUND

Several studies of prenatal determinants and neonatal morbidity and mortality among very preterm births have resulted in unexpected and paradoxical findings. We aimed to compare perinatal death rates among cohorts of very preterm births (24-31 weeks) with rates among all births in these groups (≥24 weeks), using births-based and fetuses-at-risk formulations.

METHODS

We conducted a cohort study of singleton live births and stillbirths ≥24 weeks' gestation using population-based data from the United States and Canada (2006-2015). We contrasted rates of perinatal death between women with or without hypertensive disorders, between maternal races, and between births in Canada vs the United States.

RESULTS

Births-based perinatal death rates at 24-31 weeks were lower among hypertensive than among non-hypertensive women (rate ratio [RR] 0.67, 95% CI 0.65-0.68), among Black mothers compared with White mothers (RR 0.94, 95%CI 0.92-0.95) and among births in the United States compared with Canada (RR 0.74, 95%CI 0.71-0.75). However, overall (≥24 weeks) perinatal death rates were higher among births to hypertensive vs non-hypertensive women (RR 2.14, 95%CI 2.10-2.17), Black vs White mothers (RR 1.86, 95%CI 184-1.88;) and births in the United States vs Canada (RR 1.08, 95%CI 1.05-1.10), as were perinatal death rates based on fetuses-at-risk at 24-31 weeks (RR for hypertensive disorders: 2.58, 95%CI 2.53-2.63; RR for Black vs White ethnicity: 2.29, 95%CI 2.25-2.32; RR for United States vs Canada: 1.27, 95%CI 1.22-1.30).

CONCLUSION

Studies of prenatal risk factors and between-centre or between-country comparisons of perinatal mortality bias causal inferences when restricted to truncated cohorts of very preterm births.

Maternal age and long-term neurodevelopmental outcomes of preterm infants < 29 weeks gestational age

OBJECTIVE

The objective of this study is to assess the impact of maternal age on neurodevelopmental (ND) outcomes of infants < 29 weeks gestational age (GA) at 18-24 months.

STUDY DESIGN

A retrospective cohort study of preterm infants < 29 weeks GA admitted to Canadian tertiary NICUs was performed. The primary outcome was a composite of death or ND impairment (NDI)/significant NDI (sNDI) at 18-24 months. Association between maternal age and outcome was assessed across maternal age groups (15-19, 20-34, 35-39 and ≥40 years) using logistic regression after adjusting for confounders.

RESULTS

Of 3691 eligible infants, 2652 with complete data were included in the analysis. Significant differences in maternal characteristics existed across age groups. The only difference in neonatal characteristics was the incidence of bronchopulmonary dysplasia (p < 0.01). There was no association between maternal age and death or NDI/sNDI after controlling for confounders.

CONCLUSION

Maternal age is not associated with differences in NDI/sNDI rates among Canadian preterm infants < 29 weeks GA.

Retinopathy of Prematurity and Assisted Reproductive Technology: Is There an Association?

Purpose

This study aimed to determine the incidence of retinopathy of prematurity (ROP) and to assess whether assisted reproductive technology (ART) is a risk factor for ROP independent of the generation of multiple births by determining the occurrence and severity of ROP and the need for treatment. We will also evaluate other risk factors associated with the development of ROP among preterm infants.

Patients and Methods

We conducted a retrospective chart review for all premature infants who were screened for ROP according to the screening guidelines of the American Academy of Ophthalmology and born at King Abdulaziz University Hospital from 2015 to 2019. In addition to ophthalmological results, data on gestational age (GA), birth weight (BW), type of pregnancy (singleton or multiple), type of conception (natural or ART), infantile factors, and maternal factors were recorded.

Results

A total of 229 preterm babies met our criteria. The mean GA at birth was 29.35 weeks. Notably, 175 neonates were conceived naturally and 54 were conceived by ART. Furthermore, 33 infants in the natural conception group were products of multiple pregnancies, as were 49 infants in the ART group. ROP was noted in 96 of 229 infants (41.92%). No significant difference was found in the occurrence of ROP between multiple neonates in the natural and ART groups. However, ART birth babies in general were significantly associated with the development of ROP (P=0.045). On multiple regression analysis, early GA, low BW, and extended oxygen therapy were the variables most significantly associated with ROP (P≤0.001).

Conclusion

In our sample, ART in multiple birth babies per se did not seem to be a risk factor for ROP. However, ART babies were more prone to develop ROP than natural conception birth babies, which seemed to be more severe.

Neonatal Morbidity and Mortality in Advanced Aged Mothers-Maternal Age Is Not an Independent Risk Factor for Infants Born Very Preterm

Background: As childbearing is postponed in developed countries, maternal age (MA) has increased over decades with an increasing number of pregnancies between age 35-39 and beyond. The aim of the study was to determine the influence of advanced (AMA) and very advanced maternal age (vAMA) on morbidity and mortality of very preterm (VPT) infants. Methods: This was a population-based cohort study including infants from the "Effective Perinatal Intensive Care in Europe" (EPICE) cohort. The EPICE database contains data of 10329 VPT infants of 8,928 mothers, including stillbirths and terminations of pregnancy. Births occurred in 19 regions in 11 European countries. The study included 7,607 live born infants without severe congenital anomalies. The principal exposure variable was MA at delivery. Infants were divided into three groups [reference 18-34 years, AMA 35-39 years and very(v) AMA ≥40 years]. Infant mortality was defined as in-hospital death before discharge home or into long-term pediatric care. The secondary outcome included a composite of mortality and/or any one of the following major neonatal morbidities: (1) moderate-to-severe bronchopulmonary dysplasia; (2) severe brain injury defined as intraventricular hemorrhage and/or cystic periventricular leukomalacia; (3) severe retinopathy of prematurity; and (4) severe necrotizing enterocolitis. Results: There was no significant difference between MA groups regarding the use of surfactant therapy, postnatal corticosteroids, rate of neonatal sepsis or PDA that needed pharmacological or surgical intervention. Infants of AMA/vAMA mothers required significantly less mechanical ventilation during NICU stay than infants born to non-AMA mothers, but there was no significant difference in length of mechanical ventilation and after stratification by gestational age group. Adverse neonatal outcomes in VPT infants born to AMA/vAMA mothers did not differ from infants born to mothers below the age of 35. Maternal age showed no influence on mortality in live-born VPT infants. Conclusion: Although AMA/vAMA mothers encountered greater pregnancy risk, the mortality and morbidity of VPT infants was independent of maternal age.

A compelling symmetry: The extended fetuses-at-risk perspective on modal, optimal and relative birthweight and gestational age

BACKGROUND

The relationship between several intriguing perinatal phenomena, namely, modal, optimal, and relative birthweight and gestational age, remains poorly understood, especially the mechanism by which relative birthweight and gestational age resolve the paradox of intersecting perinatal mortality curves.

METHODS

Birthweight and gestational age distributions and birthweight- and gestational age-specific perinatal death rates of low- and high-risk cohorts in the United States, 2004-2015, were estimated using births-based and extended fetuses-at-risk formulations. The relationships between these births-based distributions and rates, and the first derivatives of fetuses-at-risk birth and perinatal death rates were examined in order to assess how the rate of change in fetuses-at-risk rates affects gestational age distributions and births-based perinatal death rate patterns.

RESULTS

Modal gestational age typically exceeded optimal gestational age because both were influenced by the peak in the first derivative of the birth rate, while optimal gestational age was additionally influenced by the point at which the first derivative of the fetuses-at-risk perinatal death rate showed a sharp increase in late gestation. The clustering and correlation between modal and optimal gestational age within cohorts, the higher perinatal death rate at optimal gestational age among higher-risk cohorts, and the symmetric left-shift in births-based gestational age-specific perinatal death rates in higher-risk cohorts explained how relative gestational age resolved the paradox of intersecting perinatal mortality curves.

CONCLUSIONS

Changes in the first derivative of the fetuses-at-risk birth and perinatal death rates underlie several births-based perinatal phenomena and this explanation further unifies the fetuses-at-risk and births-based models of perinatal death.

Maternal smoking as an independent risk factor for the development of severe retinopathy of prematurity in very preterm infants

BACKGROUND/OBJECTIVES

Retinopathy of prematurity (ROP) is a severe neonatal complication potentially leading to visual impairment and blindness. Known risk factors include preterm birth, low birth weight and respiratory support. Limited and contradictory data exist on the risk of maternal smoking during pregnancy on the development of ROP. This study aims to investigate smoking as an independent risk factor for the development of severe ROP (≥stage 3).

SUBJECTS/METHODS

This is a single centre retrospective case-control study of prospectively collected clinical data of infants born before 32 weeks of gestation between 2001 and 2012 at a tertiary care university hospital. The association between maternal smoking during pregnancy and the development of severe ROP was analyzed by multivariate logistic regression.

RESULTS

In total, n = 751 infants born < 32 weeks of gestation were included in this study. In total, 52.9% (n = 397) were diagnosed with ROP and 10.8% (n = 81) developed ROP ≥ stage 3. In total, 8.4% (n = 63) mothers presented with a history of smoking during pregnancy, which was associated to a higher rate of ROP (OR 2.59, 95% CI 1.10-6.12). Low gestational age, low birth weight and prolonged respiratory support were confirmed as independent risk factors for the development of severe ROP.

CONCLUSIONS

To date, this is the largest study evaluating the effect of maternal smoking on the development of ROP. Maternal smoking during pregnancy is identified as an independent risk factor for the development of severe ROP in preterm infants born < 32 weeks of gestation.

Maternal age and the risk of adverse pregnancy outcomes: a retrospective cohort study

BACKGROUND

The increased potential for negative pregnancy outcomes in both extremes of reproductive age is a well-debated argument. The aim of this study was to analyze the prevalence and the outcome of pregnancies conceived at extreme maternal ages.

METHODS

This retrospective study considered all single consecutive pregnancies delivered in a tertiary referral center between 2001 and 2014. Patients were categorized into 4 groups according to maternal age at delivery (< 17 years; 18-28 years; 29-39 years; > 40 years). The following outcomes were considered (amongst others): pregnancy-related hypertensive disorders (PRHDs), neonatal resuscitation (NR), neonatal intensive care unit (NICU) admission, periventricular leucomalacia (PVL), and grade 3 and 4 intraventicular hemorrhage (IVH).

RESULTS

During the considered period 22,933 single pregnancies gave birth in our unit. We observed 71 women aged < 17 years, and 1552 aged > 40 years. In each year throughout the study period, there was a significant increment in maternal age of 0.041 years (95% CI 0.024-0.058) every new year. Multivariate analysis concluded out that maternal age over 40 years was an independent risk factor for preterm delivery (OR 1.36 95% CI 1.16-1.61, p < 0.05, PRHDs (OR 2.36 95% CI 1.86-3.00, p < 0.05), GDM (OR 1.71 95% CI 1.37-2.12, p < 0.05) cesarean section (OR 1.99 95% CI 1.78-2.23, p < 0.05), abnormal fetal presentation (OR 1.29 95% CI 1.03-1.61, p < 0.05), and fetal PVL (OR 3.32 95% CI 1.17-9.44, p < 0.05). We also observed that maternal age under 17 years or over 40 years was an independent risk factor for grade 3 or 4 neonatal IVH (OR 2.97 95% CI 1.24-7.14, p < 0.05).

CONCLUSIONS

These findings confirm a negative impact of extreme maternal ages on pregnancy. These results should be carefully taken into account by maternal care providers in order to inform women adequately, supporting them in understanding potential risks associated with their procreation choices, and to improve clinical surveillance.

Does extreme maternal age still act as a risk factor for adverse perinatal outcome? Evidence from Poland 20 years after the social and economic transformation

It was examined whether positive changes in maternal SES and medical facilities in Poland 20 years after social and economic transformation weakened the role of maternal age in shaping perinatal outcome. Data comprised of 2,979 children born in 2000 and 2,992 – born in 2015. To test the differences between the frequency of indicators of adverse perinatal outcome the chi-square test was applied. The influence of maternal age on the perinatal outcome was estimated using Generalized Linear Models (GLMs), with binomial error distribution and the logit link function. The infants survival was examined using survival analysis. Gestational age and birth weight were influenced by mother’s age and the year of survey. Infants of adolescent and older mothers represented the groups with a risk of adverse perinatal outcome: an increase of preterm births and higher risk of having children with LBW in the group of adolescent mothers than in mothers aged >35, infants born SGA and LGA found in both adolescent and adult mothers. GLMs confirmed the impact of maternal age and the year of survey on perinatal outcome. The Cox proportional hazard models showed that the year of survey was the only factor affecting the risk of infants’ death. The impact of maternal age on adverse perinatal outcome can be counterbalanced by positive changes in social and economic standard of living of women, improvement in neonatal medical care and better equipment of hospital wards in 2015 as compared to 2000.

Towards a unified perinatal theory: Reconciling the births-based and fetus-at-risk models of perinatal mortality

BACKGROUND

There is a need to reconcile the opposing perspectives of the births-based and fetuses-at-risk models of perinatal mortality and to formulate a coherent and unified perinatal theory.

METHODS

Information on births in the United States from 2004 to 2015 was used to calculate gestational age-specific perinatal death rates for low- and high-risk cohorts. Cubic splines were fitted to the fetuses-at-risk birth and perinatal death rates, and first and second derivatives were estimated. Births-based perinatal death rates, and fetuses-at-risk birth and perinatal death rates and their derivatives, were examined to identify potential inter-relationships.

RESULTS

The rate of change in the birth rate dictated the pattern of births-based perinatal death rates in a triphasic manner: increases in the first derivative of the birth rate at early gestation corresponded with exponential declines in perinatal death rates, the peak in the first derivative presaged the nadir in perinatal death rates, and late gestation declines in the first derivative coincided with an upturn in perinatal death rates. Late gestation increases in the first derivative of the fetuses-at-risk perinatal death rate matched the upturn in births-based perinatal death rates. Differences in birth rate acceleration/deceleration among low- and high-risk cohorts resulted in intersecting perinatal mortality curves.

CONCLUSION

The first derivative of the birth rate links a cohort's fetuses-at-risk perinatal death rate to its births-based perinatal death rate, and cohort-specific differences in birth rate acceleration/deceleration are responsible for the intersecting perinatal mortality curves paradox. This mechanistic explanation unifies extant models of perinatal mortality and provides diverse insights.

The impact of advanced maternal age on the outcomes of very low birth weight preterm infants

The association between advanced maternal age and neonatal outcomes remains controversial. This study attempted to determine the short-term and long-term outcomes of very low birth weight (VLBW, <1500 g) preterm infants, born to mothers of advanced age (≥35 years).In this retrospective cohort study, VLBW infants were divided into the advanced maternal age group and comparison group. We compared the pregnancy complications, demographic factors, short-term morbidities, and neurodevelopmental outcomes using the Bayley Scales of Infant Development-Third Edition, at 24 months of corrected age between the 2 groups.The study comprised of 536 VLBW infants born to 483 mothers. Mothers of advanced age had a significantly lower rate of primiparity compared to the comparison group (45.8% vs 65.2%, P < .001), and were more likely to have gestational diabetes (13.7% vs 5.5%, P = .002) and to undergo in vitro fertilization (IVF; 18.4% vs 9.9%, P = .01). No significant differences were found between the 2 groups in terms of short-term outcomes. At 2 years of corrected age, advanced maternal age was associated with a higher incidence of severe speech delay (11.3% vs 5.7%, P = .04), neurodevelopmental impairment (NDI; 28.8% vs 18.4%, P = .02), and adverse composite outcome (37.4% vs 27.3%, P = .02). However, the differences in NDI and composite adverse outcomes were not statistically significant between the groups after adjustments for potential confounders.Advanced maternal age was not associated with major morbidities and long-term NDI among VLBW preterm infants. The association between advanced maternal age and severe speech delay in the infant needs further investigation.

Physical fitness of non-disabled school-aged children born with extremely low birth weights

BACKGROUND

The assessment of long-term outcomes in survivors born with extremely low birth weights (ELBWs) has become increasingly important. However, little has been reported on the physical fitness of non-disabled school-aged children born with ELBWs.

AIMS

To assess the physical fitness of non-disabled school-aged children born with ELBWs.

STUDY DESIGN

Retrospective cohort study.

SUBJECTS

We analyzed 169 ELBW infants without cerebral palsy or intellectual disability (based on the Wechsler Intelligence Scale for Children-Third Edition (WISC-III) Full Scale intelligence quotient (IQ) test < 70).

OUTCOME MEASURES

Physical fitness was assessed using the grip strength, sit-up repetitions, sit & reach, side steps, standing long jump, and softball throw tests. T-scores were calculated using national survey data.

RESULTS

The T-scores for the grip strength, sit-up repetitions, sit & reach, side steps, standing long jump, softball throw tests, and the overall T-score were 43.7 ± 7.5, 44.2 ± 10.5, 46.0 ± 9.7, 40.9 ± 8.0, 40.0 ± 9.8, 42.4 ± 8.1, and 42.9 ± 5.5, respectively. After adjusting for other age-related factors, the height (SD score), WISC-III Performance IQ score, and percent predicted forced vital capacity (FVC) independently predicted the overall T-scores. Their standardized partial regression coefficients (β) were 0.334 (p = 0.009), 0.190 (p = 0.022), and 0.187 (p = 0.032), respectively.

CONCLUSIONS

Our cohort's physical fitness at approximately 8 years of age was significantly impaired compared to average Japanese children of the same age. Height, FVC, and Performance IQ independently predicted physical fitness, with height being the strongest predictor.

Pregnancy Outcomes in Women of Advanced Maternal Age: a Retrospective Cohort Study from China

This retrospective cohort study attempts to investigate pregnancy complications and adverse pregnancy outcomes in women of advanced maternal age (AMA). Data were extracted from electronic medical records system at West China Second University Hospital of Sichuan University from January 2013 to July 2016. The study cohort consisted 8 subgroups of women on 4 different age levels (20-29 years, 30-34 years, 35-39 years and ≥40 years) and 2 different parities (primiparity and multiparity). In the study period, 38811 women gave birth at our hospital, a randomized block was used to include 2800 women of singleton pregnancy >28 gestational weeks, with 350 patients in each subgroup. Maternal complications and fetal outcomes were collected and defined according to relevant guidelines. Confounding factors representing maternal demographic characteristics were identified from previous studies and analysed in multivariate analysis. There was an increasing trend for the risks of adverse pregnancy outcomes with increasing age, especially in AMA groups. Our study showed that AMA, primiparity, maternal overweight or obesity, lower educational level and residence in rural area increased pregnancy complications and adverse fetal outcomes. Increased professional care as well as public concern is warranted.

Retinopathy of prematurity: a review of risk factors and their clinical significance

Retinopathy of prematurity (ROP) is a retinal vasoproliferative disease that affects premature infants. Despite improvements in neonatal care and management guidelines, ROP remains a leading cause of childhood blindness worldwide. Current screening guidelines are primarily based on two risk factors: birth weight and gestational age; however, many investigators have suggested other risk factors, including maternal factors, prenatal and perinatal factors, demographics, medical interventions, comorbidities of prematurity, nutrition, and genetic factors. We review the existing literature addressing various possible ROP risk factors. Although there have been contradictory reports, and the risk may vary between different populations, understanding ROP risk factors is essential to develop predictive models, to gain insights into pathophysiology of retinal vascular diseases and diseases of prematurity, and to determine future directions in management of and research in ROP.

The fetuses-at-risk approach: survival analysis from a fetal perspective

Several phenomena in contemporary perinatology create challenges for analyzing pregnancy outcomes. These include recent increases in iatrogenic delivery at late preterm and early term gestation, which are incongruent with the belief that stillbirth and neonatal death risks decrease exponentially with advancing gestational age. Perinatal epidemiologists have also puzzled over the paradox of intersecting birthweight-specific and gestational age-specific perinatal mortality curves for decades. For example, neonatal mortality rates among preterm infants of women who smoke are substantially lower than neonatal mortality rates among preterm infants of non-smoking women, whereas the reverse pattern occurs at term gestation. This mortality crossover is observed across several contrasts (for example, women with hypertensive disorders of pregnancy vs. normotensive women, older vs. younger women, twins vs. singletons) and outcomes (stillbirth, neonatal death, sudden infant death syndrome and cerebral palsy), and irrespective of how advancing "maturity" is defined (birthweight or gestational age). One approach proposed to address and explain these unexpected phenomena is the fetuses-at-risk model. This formulation involves a reconceptualization of the denominator for perinatal outcome rates from births to surviving fetuses. In this overview of the fetuses-at-risk model, we discuss the central tenets of the births-based and the fetuses-based formulations. We also describe the extension of the fetuses-at-risk approach to outcomes into and beyond the neonatal period and to a multivariable adaptation. Finally, we provide a substantive context by discussing biological mechanisms underlying the fetuses-at-risk model and contemporary obstetric phenomena that are better understood from that model than from one based on births.

Methodological Challenges in International Comparisons of Perinatal Mortality

PURPOSE OF REVIEW

Several prestigious agencies routinely rank countries based on crude perinatal and infant mortality rates, while more recently, international neonatal networks have begun comparing neonatal mortality and morbidity rates among very preterm and very low-birth-weight infants. We discuss the methodologic challenges that compromise such comparisons and potential remedies.

RECENT FINDINGS

Crude perinatal mortality rates are biased by international variations in birth registration, especially at the borderline of viability. Such bias is demonstrated by significant differences in crude versus birth weight- and gestational age-specific comparisons of perinatal mortality. Comparisons of neonatal mortality among very preterm and very low-birth-weight infants are plagued by incorrect denominators, and this leads to paradoxical findings.

SUMMARY

A lack of standardization with regard to birth registration and inadequate appreciation of the methods for calculating gestational age-specific mortality rates are responsible for biasing international comparisons of perinatal mortality.

Causes of death in very preterm infants cared for in neonatal intensive care units: a population-based retrospective cohort study

Background

While there are good data to describe changing trends in mortality and morbidity rates for preterm populations, there is very little information on the specific causes and pattern of death in terms of age of vulnerability. It is well established that mortality increases with decreasing gestational age but there are limited data on the specific causes that account for this increased mortality. The aim of this study was to establish the common causes of hospital mortality in a regional preterm population admitted to a neonatal intensive care unit (NICU).

Methods

Retrospective analysis of prospectively collected data of the Neonatal Intensive Care Units' (NICUS) Data Collection of all 10 NICUs in the region. Infants <32 weeks gestation without major congenital anomalies admitted from 2007 to 2011 were included. Three authors reviewed all cases to agree upon the immediate cause of death.

Results

There were 345 (7.7%) deaths out of 4454 infants. The most common cause of death across all gestational groups was major IVH (cause-specific mortality rate [CMR] 22 per 1000 infants), followed by acute respiratory illnesses [ARI] (CMR 21 per 1000 infants) and sepsis (CMR 12 per 1000 infants). The most common cause of death was different in each gestational group (22–25 weeks [ARI], 26–28 weeks [IVH] and 29–31 weeks [perinatal asphyxia]). Pregnancy induced hypertension, antenatal steroids and chorioamnionitis were all associated with changes in CMRs. Deaths due to ARI or major IVH were more likely to occur at an earlier age (median [quartiles] 1.4 [0.3–4.4] and 3.6 [1.9–6.6] days respectively) in comparison to NEC and miscellaneous causes (25.2 [15.4–37.3] and 25.8 [3.2–68.9] days respectively).

Conclusions

Major IVH and ARI were the most common causes of hospital mortality in this extreme to very preterm population. Perinatal factors have a significant impact on cause-specific mortality. The varying timing of death provides insight into the prolonged vulnerability for diseases such as necrotising enterocolitis in our preterm population.

The interaction between maternal race/ethnicity and chronic hypertension on preterm birth

BACKGROUND

In both the biomedical and public health literature, the risk for preterm birth has been linked to maternal racial/ethnic background, in particular African-American heritage. Despite this well-documented health disparity, the relationship of comorbid conditions, such as chronic hypertension, to maternal race/ethnicity and preterm birth has received relatively limited attention in the literature.

OBJECTIVE

The objective of the study was to evaluate the interaction between chronic hypertension and maternal racial/ethnic background on preterm birth.

STUDY DESIGN

This is a retrospective cohort study of singleton pregnancies among women who delivered between 2002 and 2015 at the University of California, San Francisco. The associations of chronic hypertension with both spontaneous and medically indicated preterm birth were examined by univariate and multivariate logistical regression, adjusting for confounders including for maternal age, history of preterm birth, maternal body mass index, insurance type (public vs private), smoking, substance abuse, history of pregestational diabetes mellitus, and use of assisted reproductive technologies. The interaction effect of chronic hypertension and racial/ethnicity was also evaluated. All values are reported as odds ratios, with 95% confidence intervals and significance set at P = .05.

RESULTS

In this cohort of 23,425 singleton pregnancies, 8.8% had preterm deliveries (3% were medically indicated preterm birth, whereas 5.5% were spontaneous preterm births), and 3.8% of women carried the diagnosis of chronic hypertension. Chronic hypertension was significantly associated with preterm birth in general (adjusted odds ratio, 2.74, P < .001) and medically indicated preterm birth specifically (adjusted odds ratio, 5.25, P < .001). When evaluating the effect of chronic hypertension within racial/ethnic groups, there was an increased odds of a preterm birth among hypertensive, African-American women (adjusted odds ratio, 3.91, P < .001) and hypertensive, Asian-American/Pacific Islander women (adjusted odds ratio, 3.51, P < .001) when compared with their nonhypertensive counterparts within the same racial/ethnic group. These significant effects were also noted with regard to medically indicated preterm birth for hypertensive African-American women (adjusted odds ratio, 6.85, P < .001) and Asian-American/Pacific Islander women (adjusted odds ratio, 9.87, P < .001). There was no significant association of chronic hypertension with spontaneous preterm birth (adjusted odds ratio, 0.87, P = .4).

CONCLUSION

The effect of chronic hypertension on overall preterm birth and medically indicated preterm birth differs by racial/ethnic group. The larger effect of chronic hypertension among African-American and Asian/Pacific Islander women on medically indicated and total preterm birth rates raises the possibility of an independent variable that is not captured in the data analysis, although data regarding the indication for medically indicated preterm delivery was limited in this data set. Further investigation into both social-structural and biological predispositions to preterm birth should accompany research focusing on the effect of chronic hypertension on birth outcomes.

Maternal age and outcome of preterm infants at discharge from the neonatal intensive care unit

OBJECTIVE

To assess the effect of maternal age on preterm neonates' survival free from major morbidity at discharge from two neonatal intensive care units in Jerusalem, Israel.

METHODS

A retrospective chart review of two hospitals from 2009-2010 was performed. Eligible neonates were born at less than 35 weeks of gestation and survived to discharge. Major morbidity included at least one of the following: chronic lung disease, at least grade 3 intraventricular hemorrhage, periventricular leukomalacia, at least stage 3 retinopathy of prematurity, at least stage 2 necrotizing enterocolitis, or sepsis.

RESULTS

The analysis was performed on 380 neonates of 294 mothers. Mean maternal age was 30.5 years (range, 17-52), mean gestational age was 31.5 weeks (range, 24-34), and mean birth weight was 1705.5 g (range, 460-3150). Of the neonates, 90 (23.7%) had major morbidity, which was associated with lower mean gestational age (29.5 weeks vs 32.3 weeks, P<0.001), birth weight (1326.5g vs 1822.2g, P<0.001), and the need for resuscitation at birth (P<0.001) in comparison with neonates without major morbidity. A comparison of maternal age between the two outcome groups yielded a nonsignificant result. A logistic regression model revealed that maternal age does not contribute significantly to poor neonatal outcomes.

CONCLUSION

Advanced maternal age was not associated with major morbidity of preterm neonates at discharge from the neonatal intensive care units.

Outcome comparison of very preterm infants cared for in the neonatal intensive care units in Australia and New Zealand and in Canada

AIM

To compare risk-adjusted neonatal intensive care unit outcomes between regions of similar population demography and health-care systems in Australia-New Zealand and Canada to generate meaningful hypothesis for outcome improvements.

METHODS

Retrospective study of data from preterm infants (<32 weeks gestational age) cared for in 29 ANZNN (Australian and New Zealand Neonatal Network) and 26 Canadian Neonatal Network (CNN) intensive care unit admitted between 2005 and 2007. Moribund infants or those with major congenital malformation were excluded.

RESULTS

The 9995 ANZNN infants had a higher gestational age (29 vs. 28 weeks, P < 0.0001), lower rate of outborn status (13.2% vs. 19.1%, P < 0.0001) and Apgar score <7 at 5 min (14.8% vs. 21.6%, P < 0.0001) than their 7141 CNN counterparts. After adjustment, ANZNN and CNN infants had a similar likelihood of survival (adjusted odds ratio (AOR) 1.01 (0.88, 1.16)), but ANZNN infants were at lower risk of severe retinopathy (AOR 0.71 (0.61, 0.83)), severe ultrasound neurological injury (AOR 0.68 (0.59, 0.78)), necrotising enterocolitis (AOR 0.65 (0.56, 0.76)), chronic lung disease (AOR 0.67 (0.62, 0.73)) and late-onset sepsis (AOR 0.83 (0.76, 0.91)). ANZNN infants were at a higher risk of pulmonary air leak (AOR 1.20 (1.01, 1.42)), early-onset sepsis (AOR 1.33 (1.02, 1.74)). More ANZNN infants received any respiratory support (AOR 1.27 (1.14, 1.41)) and continuous positive airway pressure as sole respiratory support (AOR 2.50 (2.27, 2.70)).

CONCLUSIONS

Despite similarities in settings, ANZNN infants fared better in most measures. Outcome disparities may be related to differences in tertiary service provision, referral and clinical practices.

Pregnancy and Obstetrical Outcomes in Women Over 40 Years of Age

Introduction: Delayed childbearing is increasing, and advanced maternal age has been associated with an increased risk of obstetrical complications. The purpose of this study was to evaluate pregnancy outcomes in women with advanced maternal age (≥ 40 years). Methods: Maternal and obstetrical data were collected from the Department of Obstetrics and Gynecology of the University of Wuerzburg for the period from 2006 to 2011. In this retrospective analysis we compared the outcomes for women aged ≥ 40 years (n = 405) with those of three younger subgroups (I: < 30 y; II: 30-34 y; III: 35-39 y). Results: Pregnant women older than 40 years had more chronic diseases such as hypertension, needed medical treatment more frequently and had a higher thrombosis risk. Pregnancy-induced diseases such as gestational diabetes, preeclampsia and pregnancy-associated hypertension occurred more often in women ≥ 40 years of age. Compared to mothers who were younger than 30 years, primiparous women ≥ 40 years had a more than four times higher overall cesarean section rate and four times higher elective cesarean section rate. Furthermore, they required longer hospital stays, both after cesarean section and after vaginal delivery. The preterm birth rate (≤ 32 weeks of gestation) was similar across the different age groups. Conclusions: The outcomes of pregnancy and childbirth and for newborns born to women ≥ 40 years did not vary significantly from those of younger women if the following conditions were met: a) pre-existing chronic diseases were treated medically and dietetically; b) pregnancy-induced morbidity was monitored regularly and controlled medically; c) women attended regular prenatal check-ups; d) a healthy lifestyle was adhered to during pregnancy, and e) delivery occurred in a perinatal center.

What is the impact of interventions that prevent fetal mortality on the increase of preterm live births in the State of Sao Paulo, Brazil?

Background

There is a global growing trend of preterm births and a decline trend of fetal deaths. Is there an impact of the decline of fetal mortality on the increase of preterm live births in State of Sao Paulo, Brazil?

Methods

The time trends were evaluated by gestational age through exponential regression analysis. Data analyzed included the fetal mortality ratio, proportion of preterm live births, fertility rate of women 35 years and over, prenatal care, mother's education, multiple births and cesarean section deliveries. A survival analysis was carried out for 2000 and 2010.

Results

Preterm births showed the highest annual increase (3.2 %) in the less than 28 weeks of gestation group and fetal mortality ratio decreased (7.4 %) in the same gestational age group. There was an increase of cesarean section births and it was higher in the < 28 weeks group (6.1 %). There was a decreased annual trend of mothers with inadequate prenatal care (6.1 %) and low education (8.8 %) and an increased trend in multiple births and fertility rates of women of 35 years and over. The variables were highly correlated to which other over time. In 2000, 8.2 % of all pregnancies resulted in preterm births (0.9 % in fetal deaths and 7.3 % in live births). In 2010, the preterm birth increased to 9.4 % (0.8 % were preterm fetal deaths and 8.6 % preterm live births).

Conclusions

The results suggest that 45.2 % could be the maximum contribution of successful interventions to prevent a fetal death on the increase in preterm live births. This increasing trend is also related to changes of the women reproductive profile with the change of the women reproductive profile and access to prenatal care.

Gestational age-specific neonatal morbidity among pregnancies complicated by advanced maternal age: a population-based retrospective cohort study

OBJECTIVE

Compare significant neonatal morbidity frequency differences in advanced maternal age (AMA) versus non-AMA pregnancies, assessing which gestational week is associated with the lowest morbidity risk.

METHODS

Population-based retrospective cohort study. Adverse neonatal outcome frequency differences were stratified by each week of gestation. Multivariate logistic regression estimated the relative risk (RR) of composite neonatal morbidity for women aged 35-39, 40-44, 45-49 and 50-55 versus 18-34 years, adjusted sequentially for relevant risk factors.

RESULTS

Neonatal morbidity decreased with each advancing week of term gestation, lowest at 39 weeks for all the groups. Adverse neonatal outcome risk for births to AMA women increased at 40 weeks: 35-39 years adjRR 1.12 [1.01-1.24] and ≥40 years 1.24 [1.01-1.52]. Each older maternal age category had increased risk for overall neonatal morbidity: 35-39 years adjRR 1.11 [95% CI 1.08-1.15], 40-44 years 1.21 [95% CI 1.14-1.29] and 45-49 years 1.34 [95% CI 1.05-1.69].

CONCLUSIONS

Lowest neonatal morbidity risk is at 39-week gestation with a significantly increased risk observed thereafter, especially in women ≥40 years.

Fetuses-at-risk, to avoid paradoxical associations at early gestational ages: extension to preterm infant mortality

BACKGROUND

Fetuses-at-risk denominators are commonly used in research on preterm stillbirth, but applications to postnatal outcomes such as preterm infant mortality are controversial. We evaluated whether biased associations between maternal risk factors and preterm infant mortality caused by stratification by preterm birth could be avoided using fetuses-at-risk risk ratios.

METHODS

Data included 3 277 570 births drawn from the linked live birth-death file for Canada from 1990 through 2005. We used maternal age as the risk factor, and estimated the association with stillbirth, early neonatal, late neonatal and postneonatal mortality by gestational interval (22-24, 25-27, 28-31, 32-36, ≥37 weeks). Models were run using (i) log-binomial regression stratified by preterm gestational age, and (ii) unstratified log-binomial regression using fetuses-at-risk denominators.

RESULTS

Extremes of maternal age were associated with higher mortality among term births. Among preterm births, the stratified model suggested a protective, null or attenuated association of extremes of maternal age with stillbirth, early, late and post neonatal mortality. The unstratified fetuses-at-risk model, however, resulted in the expected higher risk of mortality at extremes of maternal age for all outcomes.

CONCLUSIONS

Fetuses-at-risk regression can avoid paradoxical associations between maternal exposures and mortality of infants born early in gestation, caused by preterm birth stratification bias. The fetuses-at-risk approach can be extended through the first year of life, or potentially beyond, depending on the outcome and presence of unmeasured confounders associated with preterm birth.

Bronchopulmonary dysplasia - trends over three decades

OBJECTIVES

To describe the characteristics of bronchopulmonary dysplasia (BPD) and respiratory distress syndrome subjects, along with the trends in severity and mortality associated with BPD over the past three decades.

METHODS

Retrospective study of BPD and respiratory distress syndrome subjects born between 1980 and 2008, and admitted to Montreal Children's Hospital (Montreal, Quebec). Data were abstracted from hospital records.

RESULTS

Gestational age and birth weight were correlated with the occurrence of BPD with each additional week of gestation and 100 g in birth weight being associated with an OR of developing BPD of 0.77 and 0.89, respectively. BPD severity was associated with male sex, Apgar score and the occurrence of neonatal pneumonia. Significant trends were observed for lower mortality despite lower gestational age and birth weight, greater maternal age and multiple gestations.

CONCLUSION

Mortality from BPD has improved over the past three decades despite significant trends toward more pronounced prematurity and lower birth weights.

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.

Perinatal risk factors for bronchopulmonary dysplasia in a national cohort of very-low-birthweight infants

OBJECTIVE

We sought to assess the independent effect of perinatal factors on the risk for bronchopulmonary dysplasia (BPD) in very-low-birthweight infants.

STUDY DESIGN

This was a population-based observational study. Data were prospectively collected by the Israel Neonatal Network. Multivariable analyses identified independent risk factors for BPD.

RESULTS

Of 12,139 infants surviving to a postmenstrual age of 36 weeks, 1663 (13.7%) developed BPD. BPD was independently associated with young maternal age (odds ratio [OR], 1.53), maternal hypertensive disorders (OR, 1.28), antepartum hemorrhage (OR, 1.26), male gender (OR, 1.41), non-Jewish ethnicity (OR, 1.23), birth defects (OR, 1.94), small for gestational age (GA) (OR, 2.65), and delivery room resuscitation (OR, 1.86). Stratified analysis by GA groups showed that postdelivery resuscitation had a more pronounced effect with increasing maturity.

CONCLUSION

Perinatal factors and pregnancy complications were independently associated with development of BPD in very-low-birthweight infants. Most risk factors identified were consistent within GA groups.