Preterm Period Research Articles

Late preterm second-stage of labor in relation to perinatal outcome

Nearly 70% of preterm births (PTB) are late preterm. They have higher morbidity and mortality rates than their term counterparts. Yet, no separate labor curves exist for late PTB, and the optimal duration of the second stage of labor in this group has never been defined. The aim of our study was to characterize the second stage of labor in the late preterm period in relation to perinatal outcome.

The natural history of advanced cervical dilation in the late preterm period

Women who present in preterm labor (PTL) represent a diagnostic and clinical management challenge. The timing of delivery after presentation is variable and dependent on clinical factors. Even women with advanced cervical dilation often remain pregnant for longer intervals than expected. We sought to investigate the natural history of women presenting in PTL stratified by cervical examination.

Shared Decision Making: Women Undergoing Expectant Management with Prelabor Rupture of Membranes

ACOG recommends shared decision making with regards to expectant management of prelabor rupture of membranes (PROM) beyond 34 weeks. However, implicit bias may impact counseling, while the use of a conversation aid promotes health equity. Our objective was to compare maternal and neonatal outcomes before and after implementation of a conversation aid for PROM counseling, and describe characteristics of those who underwent expectant management in the late preterm period.

The impact of premature extrauterine exposure on infants’ stimulus-evoked brain activity across multiple sensory systems

Prematurity can result in widespread neurodevelopmental impairment, with the impact of premature extrauterine exposure on brain function detectable in infancy. A range of neurodynamic and haemodynamic functional brain measures have previously been employed to study the neurodevelopmental impact of prematurity, with methodological and analytical heterogeneity across studies obscuring how multiple sensory systems are affected. Here, we outline a standardised template analysis approach to measure evoked response magnitudes for visual, tactile, and noxious stimulation in individual infants (n = 15) using EEG. By applying these templates longitudinally to an independent cohort of very preterm infants (n = 10), we observe that the evoked response template magnitudes are significantly associated with age-related maturation. Finally, in a cross-sectional study we show that the visual and tactile response template magnitudes differ between a cohort of infants who are age-matched at the time of study but who differ according to whether they are born during the very preterm or late preterm period (n = 10 and 8 respectively). These findings demonstrate the significant impact of premature extrauterine exposure on brain function and suggest that prematurity can accelerate maturation of the visual and tactile sensory system in infants born very prematurely. This study highlights the value of using a standardised multi-modal evoked-activity analysis approach to assess premature neurodevelopment, and will likely complement resting-state EEG and behavioural assessments in the study of the functional impact of developmental care interventions.

Does antenatal corticosteroid therapy improve neonatal outcomes in late preterm birth?

Background Infants who are born at 34°/7 to 366/7 weeks of gestation (late preterm) are at greater risk for respiratory and other neonatal morbidities. The objective of this study was to examine the effects of the administration of antenatal corticosteroids (ACS) to women at risk for late preterm delivery on the incidence of neonatal outcomes. Method This was a prospective cohort study of singleton gestations at risk of imminent delivery between 34°/7 and 366/7 weeks. Neonatal outcomes were compared between mothers who received ACS and those who did not. The primary outcome was the rate of composite respiratory morbidity defined as the need for treatment within 72 h of life (continuous positive airway pressure or high flow nasal cannula for least 2 h or supplemental oxygen with a fraction of inspired oxygen of at least 0.30 for at least four continuous hours or mechanical ventilation). Results During the 3-year study period, 595 subjects were included in this study, comprising 234 subjects that received ACS and 361 that did not. Administration of ACS significantly reduced the rates of composite respiratory morbidity (aOR 0.63 95% CI 0.40–0.99), the use of CPAP or HFNC for at least 2 h (aOR 0.57 95% CI 0.35–0.94), and transient tachypnea of the newborn (aOR 0.48 95% CI 0.28–0.82). Neonatal hypoglycemia was more significantly increased in the ACS group compared with controls (aOR 1.64 95% CI 1.04–2.59). We found no significant between-group differences in the rate of respiratory distress syndrome, surfactant use, need for resuscitation, jaundice requiring phototherapy, admission to neonatal intensive care or special care nursery, and duration of hospitalization. Conclusion Administration of ACS during the late preterm period decreased neonatal respiratory complications, however, increased the rate of hypoglycemia.

The effects of betamethasone on clinical outcome of the late preterm neonates born between 34 and 36\u2009weeks of gestation

BackgroundPrenatal corticosteroid administration in preterm labor is one of the most important treatments available to improve neonatal outcomes; however, its beneficial effects on late preterm infants (after the 34th week of gestation) remained unknown. We aimed to assess the effects of betamethasone on the clinical condition of the late preterm infants born between 34 and 36 weeks of gestation.MethodsThis retrospective cohort study was performed on 100 consecutive infants born between 34 and 36 weeks of gestation and received betamethasone before delivery as the cases and 100 neonates with the same delivery conditions but without receiving betamethasone. All neonates were followed up within hospitalization to assess the neonatal outcome.ResultsThe neonates receiving betamethasone suffered more from respiratory distress syndrome (49% versus 31%, p = 0.008, RR = 1.59 95% CI (1.12–2.27)) and requiring more respiratory support (71% versus 50%, p = 0.002, RR = 1.43 95% CI (1.13–1.80)) as compared to the control group. There was no difference between the two groups in other neonatal adverse events or death.Conclusionthe use of betamethasone in the late preterm period (after 34 weeks of gestation) has no beneficial effects on lung maturity or preventing neonatal adverse outcomes, even may lead to increase the risk for RDS and requiring respiratory support.

Current Resources for Evidence-Based Practice, November 2021

An extensive review of new resources to support the provision of evidence-based care for women and infants. The current column includes a discussion of autonomy and respect in maternity care and commentaries on reviews focused on whether to induce women who present with mild preeclampsia in the late preterm period and the extent to which urinary incontinence symptoms prevent women from participating in exercise. It also includes a brief update about the USPSTF guidelines on screening for gestational diabetes.

Uterine myomas: effect of prior myomectomy on pregnancy outcomes

Objective Reproductive aged women with fibroids must weigh the risks and benefits of preconception myomectomy. Women with fibroids may have higher rates of fetal growth restriction (FGR) and stillbirth; however, there is a paucity of data on the impact of myomectomy on pregnancy outcomes. We compared perinatal outcomes in women with prior myomectomy versus those with no prior myomectomy and at least one fibroid ≥ 5 cm. Methods Retrospective cohort study of women at a single center who delivered between 2008 and 2017 with a viable intrauterine pregnancy at initial ultrasound scan and either prior myomectomy, or, in the no-myomectomy cohort, at least one fibroid ≥ 5 cm on a prenatal scan performed at < 21 weeks’ gestation (wga). Pregnancies complicated by major congenital anomalies were excluded. Primary outcome was preterm birth (PTB) < 37wga. Secondary outcomes included rates of spontaneous loss, cesarean delivery (CD), abnormal placentation, malpresentation, FGR, birthweight, birthweight percentile, estimated blood loss (EBL), blood transfusion, and neonatal survival to discharge. Results A total of 290 women met inclusion criteria: 70 had a prior myomectomy, 220 women had ≥1 fibroid ≥5cm. Women with prior myomectomy were older, more likely to have private insurance, and more likely used artificial reproductive technology to conceive; 20% with prior myomectomy still had at least one ≥ 5 cm myoma on their obstetric scan. Rates of spontaneous loss were lower in the prior myomectomy group (1.4% vs 7.3%; p = .08). Of the 273 pregnancies continuing beyond 20 weeks, women with prior myomectomy had significantly more PTBs (35% vs. 21%, p = .02) and significantly different primary birth indications (p < .0001). However, after controlling for late preterm, prelabor cesareans recommended by providers in the myomectomy cohort, the difference in PTB rates was not significant (p = .13). The myomectomy group had more CDs (88% vs. 53%, p < .0001), higher EBL (1250 mL vs. 811 mL, p = .04), and a trend toward more blood transfusions (16% vs 8%, p = .05). Other selected outcomes were similar, including rates of FGR. Conclusions Women with prior myomectomy had significantly more PTBs, due in part to more preterm, prelabor cesareans in the late preterm period. Otherwise, prior myomectomy did not confer appreciable obstetric or perinatal benefits, as patients had more CDs, and higher EBL. Recommendations to perform preterm prelabor cesareans in this population may explain some of the PTB disparity. The effect of prior myomectomy on early pregnancy loss and infertility requires further study.

Antenatal corticosteroids and neurodevelopmental outcomes in late preterm births

ObjectivesAntenatal corticosteroids (ACS) decrease neonatal mortality and morbidity among preterm neonates, yet there has been concern regarding their long-term safety. We hypothesised that potential long-term adverse effects of ACS may...

Society for Maternal-Fetal Medicine Consult Series #58: Use of antenatal corticosteroids for individuals at risk for late preterm delivery: Replaces SMFM Statement #4, Implementation of the use of antenatal corticosteroids in the late preterm birth period in women at risk for preterm delivery, August 2016

The administration of antenatal corticosteroids has been widely adopted as the standard of care in the management of pregnancies at risk for preterm delivery before 37 weeks of gestation, with the primary goal of reducing neonatal morbidity. However, the long-term risks associated with antenatal corticosteroid use remain uncertain. The purpose of this Consult is to review the current literature on the benefits and risks of antenatal corticosteroid use in the late preterm period and to provide recommendations based on the available evidence. The recommendations by the Society for Maternal-Fetal Medicine are as follows: (1) we recommend offering a single course of antenatal corticosteroids (2 doses of 12 mg of intramuscular betamethasone 24 hours apart) to patients who meet the inclusion criteria of the Antenatal Late Preterm Steroids trial, ie, those with a singleton pregnancy between 34 0/7 and 36 6/7 weeks of gestation who are at high risk of preterm birth within the next 7 days and before 37 weeks of gestation (GRADE 1A); (2) we suggest consideration for the use of antenatal corticosteroids in select populations not included in the original Antenatal Late Preterm Steroids trial, such as patients with multiple gestations reduced to a singleton gestation on or after 14 0/7 weeks of gestation, patients with fetal anomalies, or those who are expected to deliver in <12 hours (GRADE 2C); (3) we recommend against the use of antenatal corticosteroids for fetal lung maturity in pregnant patients with a low likelihood of delivery before 37 weeks of gestation (GRADE 1B); (4) we recommend against the use of late preterm corticosteroids in pregnant patients with pregestational diabetes mellitus, given the risk of worsening neonatal hypoglycemia (GRADE 1C); (5) we recommend that patients at risk for late preterm delivery be thoroughly counseled regarding the potential risks and benefits of antenatal corticosteroid administration and be advised that the long-term risks remain uncertain (GRADE 1C).

Stillbirth as left truncation for early neonatal death in California, 1989\u20132015: a time-series study

BackgroundSome scholars posit that attempts to avert stillbirth among extremely preterm gestations may result in a live birth but an early neonatal death. The literature, however, reports no empirical test of this potential form of left truncation. We examine whether annual cohorts delivered at extremely preterm gestational ages show an inverse correlation between their incidence of stillbirth and early neonatal death.MethodsWe retrieved live birth and infant death information from the California Linked Birth and Infant Death Cohort Files for years 1989 to 2015. We defined the extremely preterm period as delivery from 22 to < 28 weeks of gestation and early neonatal death as infant death at less than 7 days of life. We calculated proportions of stillbirth and early neonatal death separately by cohort year, race/ethnicity, and sex. Our correlational analysis controlled for well-documented declines in neonatal mortality over time.ResultsCalifornia reported 89,276 extremely preterm deliveries (live births and stillbirths) to Hispanic, non-Hispanic (NH) Black, and NH white mothers from 1989 to 2015. Findings indicate an inverse correlation between stillbirth and early neonatal death in the same cohort year (coefficient: -0.27, 95% CI of − 0.11; − 0.42). Results remain robust to alternative specifications and falsification tests.ConclusionsFindings support the notion that cohorts with an elevated risk of stillbirth also show a reduced risk of early neonatal death among extremely preterm deliveries. Results add to the evidence base that selection in utero may influence the survival characteristics of live-born cohorts.

Late preterm births: neonatal mortality and morbidity in twins vs. singletons

Objective To examine the outcomes of twins and singletons in the late preterm period. Materials and methods This is a retrospective cohort study of data obtained for 165,894 births in California who delivered between 34 + 0 and 36 + 6 weeks. The primary outcome was neonatal and infant mortality. The secondary outcomes included the following neonatal morbidities: respiratory distress syndrome (RDS), intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), seizure, and sepsis. Univariate analysis was performed using chi-square test and multivariable logistic regression was used to adjust for potential confounders. Results There were 143,891 singleton and 22,003 twin gestations included in the study. There was no difference in the primary outcome, neonatal and infant mortality between twins and singletons delivered at 34 and 36 weeks. After controlling for multiple potential confounders, significant differences in secondary outcomes of neonatal morbidity were identified. At 34 weeks, twins had significantly higher rates of IVH (aOR 2.47 (95%CI 1.08–5.64)), NEC (aOR 2.46 (95%CI 1.42–4.29)), RDS (aOR 1.60 (95%CI 1.45–1.77)), and sepsis (aOR 1.19 (95%CI 1.05–1.34)) compared to singletons. By 36 weeks, only an increased risk of RDS persisted among twins. Conclusions While there was no difference in mortality among twins and singletons in the late preterm period, twins may have significantly increased neonatal morbidity compared to singletons delivered between 34 + 0 and 36 + 6 weeks.

Late prematuriteit: een risicopopulatie?

Late preterm infant: a population at risk? Late preterm infants, infants born between 34 0/7 and 36 6/7 weeks of gestation, were called near term before 2005, which may lead to the assumption that they are mature and an underestimation of their risks. Late preterm infants are physiologically and metabolically immature. Compared to term infants they have increased morbidity rates, including problems such as hypothermia, hypoglycemia, hyperbilirubinemia, feeding difficulties and respiratory and immunological issues. In late preterm infants there are increased mortality rates, prolonged hospitalizations at birth, more readmissions and higher healthcare costs. The infants also have a higher risk of neurological and developmental problems and long-term respiratory, cardiovascular and metabolic difficulties. Despite their relative size and apparently mature appearance, late preterm infants should not be treated like term infants. They require careful monitoring immediately after birth, as well as during childhood and even adolescence. Child-birth should not be scheduled during the late preterm period without medical indication. The risk of continuing the pregnancy must be weighed against the risk of premature birth. The prevention and a better monitoring of late preterm infants can lead to healthcare savings.

Time interval from late preterm antenatal corticosteroid administration to delivery and the impact on neonatal outcomes

Although administration of antenatal corticosteroids has been shown to decrease neonatal respiratory morbidity when given to women at risk for late preterm birth, the time interval from antenatal corticosteroid administration to delivery that is associated with the greatest neonatal benefit remains unknown. This study aimed to evaluate whether the time interval from administration of late preterm antenatal corticosteroids to delivery is associated with a change in the likelihood of transient tachypnea of the newborn, respiratory distress syndrome, and hypoglycemia. This was a retrospective cohort study of all singleton neonates who were exposed to 1 or 2 doses of antenatal corticosteroids in the late preterm period (34+0 to 36+6 weeks' gestation) within a large healthcare system between November 2017 and March 2020. Neonates exposed to antenatal corticosteroids before 34 weeks' gestation and those with major fetal structural malformations and chromosomal disorders were excluded. Cases were stratified into the following groups based on the time interval from the first dose of antenatal corticosteroid administration to delivery: <2 days, 2 to 7 days, and >7 days. The primary outcome of transient tachypnea of the newborn was compared among the 3 groups. Secondary outcomes included respiratory distress syndrome and hypoglycemia. A multivariable logistic regression was performed to evaluate the association between the time interval and neonatal outcomes while adjusting for potential confounders. For each outcome, delivery within 2 to 7 days from the first dose of betamethasone administration was defined as the reference group. Data were presented as adjusted odds ratios with 95% confidence intervals, and statistical significance was defined as P < .05. The study cohort comprised 1248 neonates. Of those, 649 (52%) were exposed to 1 dose of antenatal corticosteroids. There were statistically significant differences in the maternal characteristics such as nulliparity, pregnancies complicated by hypertensive disorders and fetal growth restriction, gestational age at antenatal corticosteroid administration, gestational age at delivery, and mode of delivery among the 3 groups. There was a significantly increased risk for transient tachypnea of the newborn (adjusted odds ratio, 4.81; 95% confidence interval, 1.72-12.92) and respiratory distress syndrome (adjusted odds ratio, 9.86; 95% confidence interval, 1.15-84.24) associated with delivery <2 days of antenatal corticosteroid administration. The risk for hypoglycemia was highest in the delivery <2 days group (adjusted odds ratio, 3.44; 95% confidence interval, 2.10-5.63) and decreased as the time interval from antenatal corticosteroid administration to delivery increased (adjusted odds ratio, 0.32; 95% confidence interval, 0.20-0.51 for delivery >7 days). Adverse neonatal outcomes such as transient tachypnea of the newborn, respiratory distress syndrome, and hypoglycemia are more common when late preterm birth occurs <2 days after antenatal corticosteroid administration when compared with birth 2 to 7 days after administration. In addition, delivery >7 days after antenatal corticosteroid administration is associated with a decreased risk for hypoglycemia. Understanding the impact of antenatal corticosteroid timing on neonatal outcomes is essential in caring for patients at risk for late preterm birth.

Practice patterns in the administration of late preterm antenatal corticosteroids

BACKGROUNDGiven the unpredictable nature of preterm birth and the short-term impact of antenatal corticosteroids on neonatal outcomes, optimal timing of antenatal corticosteroid administration (2–7 days from expected birth) remains challenging.OBJECTIVEWe set out to evaluate the likelihood of delivery between 2 and 7 days after antenatal corticosteroid administration in the late preterm period and whether this differs based on the indication for corticosteroid administration.STUDY DESIGNRetrospective cohort of all singletons that received antenatal corticosteroids in the late preterm period (34 0/7 to 36 6/7 weeks’ gestation) and delivered within a large health system between November 2017 and March 2020. Women who received antenatal corticosteroids before the late preterm period, major fetal structural malformations, and cases with missing data were excluded. Cases were stratified on the basis of the indication for antenatal corticosteroid administration, that is, anticipated spontaneous late preterm birth or medically indicated late preterm birth. The primary outcome was delivery between 2 and 7 days after the administration of the first dose of antenatal corticosteroids. Secondary outcomes included time interval from antenatal corticosteroid administration to delivery and delivery during the first 2 days or later than 7 days after antenatal corticosteroid administration. Multivariable logistic regression was performed to evaluate factors associated with optimal timing while adjusting for potential confounders.RESULTSOf the 1238 patients included in the study, 656 (53%) delivered within the first day after antenatal corticosteroid administration and thus received only the first of 2 doses. Regardless of the indication for late preterm antenatal corticosteroid administration, the likelihood of delivery between 2 and 7 days later was 13.3% (165 of 1238). Moreover, it was more common (23.4% vs 5.0%; P≤.001) (Table 2) and more likely (adjusted odds ratio, 5.88; 95% confidence interval, 4.00–9.09) in women at risk of medically indicated preterm birth than in those with anticipated spontaneous preterm birth. Furthermore, women with anticipated spontaneous preterm birth had a shorter time interval from antenatal corticosteroid administration to delivery (10.7 vs 49.71 hour; P≤.001).CONCLUSIONRegardless of the indication for late preterm antenatal corticosteroid administration, the likelihood of delivery between 2 and 7 days later was low. Nevertheless, our data suggested that delivery within the desired time interval of antenatal corticosteroid administration is more common in women at risk of medically indicated late preterm birth compared with those at risk of spontaneous late preterm birth.

Ethical challenges in management of critically ill pregnant patients with coronavirus disease 2019 (COVID-19).

Despite the overwhelming number of coronavirus disease 2019 (COVID-19) cases worldwide, data regarding the optimal clinical guidance in pregnant patients is not uniform or well established. As a result, clinical decisions to optimize maternal and fetal benefit, particularly in patients with critical COVID-19 in the early preterm period, continue to be a challenge for obstetricians. There is often uncertainty in clinical judgment about fetal monitoring, timing of delivery, and mode of delivery because of the challenge in balancing maternal and fetal interests in reducing morbidity and mortality. The obstetrician and critical care team should empower pregnant patients or their surrogate decision maker to make informed decisions in response to the team's clinical evaluation. A clinically grounded ethical framework, based on the concepts of the moral management of medical uncertainty, beneficence-based obligations, and preventive ethics, should guide the decision-making process.

Influence of reservoir construction on surrounding vegetation cover

Vegetation is a significant factor in the energy and water cycles. Changes in vegetation are affected by the natural environment and human activities. In this study, the Dalong Reservoir on the Ningyuan River in Sanya, Hainan, was taken as an example to set one type of buffer zone with the reservoir dam site as the center, and two types of horizontal and vertical buffer zones outwards from both banks of the river, and Landsat 5 remote sensing image data and the vegetation data were applied. A coverage estimation model was used to study the temporal and spatial changes in surface vegetation in three types of buffer zones, and the characteristics of the surface vegetation changes in the preterm, midterm and late-term reservoir construction periods were analyzed. The results showed that, (1) During the years of 2000 and 2010, the vegetation coverage first decreased and then increased with time in the scope of the research. During preterm construction (2000-2004), the vegetation coverage in the upstream region decreased while that in the downstream region increased. During midterm construction (2004-2006), the declining rate of vegetation coverage downstream was greater than that upstream, but the influence of reservoir construction on vegetation coverage decreased over time in the late-term construction period (2007-2010); (2) Along the direction of the river length, the vegetation coverage showed a downtrend along with the river flow direction during the whole period (2000-2010), and the influence of reservoir construction on vegetation coverage gradually decreased as the distance from the reservoir increased; (3) Along the direction of the river width, the vegetation coverage in the preterm and midterm construction periods (2000-2006) increased with increasing distance from the riverbanks; (4) The vegetation coverage showed a significant increasing trend with increasing distance from the reservoir. The research results can provide a theoretical reference for reducing the risk of vegetation degradation, strengthening the governance of the ecological environment, and promoting the ecological construction of “landscapes, forests, fields, lakes and grass”. Keywords: reservoir, remote sensing, vegetation coverage, ecological environment, landscapes DOI: 10.25165/j.ijabe.20211403.5344 Citation: Liu P, Li X R, Zhang R K, Yao M R, Chen J F, Li Y R, et al. Influence of reservoir construction on surrounding vegetation cover. Int J Agric & Biol Eng, 2021; 14(3): 214–220.

Race and neonatal respiratory morbidity in the late preterm period

Prematurity is one of the leading causes of perinatal morbidity and mortality. Some studies suggest that respiratory disease may differ by race in early preterm infants. However, the role of race in late preterm neonatal morbidity is not yet established. The objective of our study was to determine whether neonatal respiratory morbidity differs by race in neonates born late preterm. This was a secondary analysis of a randomized trial of women at high risk for late preterm delivery (Antenatal Late Preterm Steroids). Our study was limited to women with nonanomalous, singleton gestations, delivering between 34+0 to 36+6 weeks. Women were categorized into 4 groups by race: Black, White, Asian, or other/mixed. The primary outcome was a neonatal composite of treatment in the first 72 hours (continuous positive airway pressure or high-flow nasal cannula >2 hours, oxygen >4 hours, extracorporeal membrane oxygenation or mechanical ventilation) or stillbirth or neonatal death before 72 hours. The secondary outcomes included severe respiratory morbidity (the primary outcome extending continuous positive airway pressure or high-flow nasal cannula to >12 continuous hours and oxygen to at least 24 continuous hours), respiratory distress syndrome, transient tachypnea of the newborn, apnea, neonatal intensive care unit admission, bronchopulmonary dysplasia, and surfactant administration. The primary and secondary outcomes were assessed in the active (steroid) and placebo groups separately. We fit a logistic regression model to adjust for confounders related to respiratory morbidity. Of a total of 2331 included women, 26.9% (n=627) were Black/African American, 57.1% (n=1333) White, 3.56% (n=83) Asian, and 12.36% (n=288) were other/mixed. In the placebo group, the rate of the primary outcome was significantly higher in Whites (18.6%) and Asians (22.8%) compared with the African American/Black group (12.3%) (P=.03). Adjusting for confounders, the primary outcome was not significant between the groups. The primary predictor for respiratory morbidity was a prior pregnancy with neonatal respiratory morbidity. Findings were similar in the steroid group, but severe respiratory morbidity was less common in Black infants compared with White infants (adjusted odds ratio, 0.45; 95% confidence interval, 0.24-0.83). However, a prior pregnancy with neonatal respiratory complications was no longer associated with respiratory morbidity after receipt of betamethasone. Late preterm respiratory morbidity was similar between racial groups. Although a history of pregnancy with previous neonatal respiratory disease is the strongest risk factor for recurrence, this risk factor is mitigated by the receipt of steroids.

Preeclampsia and late fetal growth restriction.

There is a strong but complex relationship between fetal growth restriction and preeclampsia. According to the International Society for the Study of Hypertension in Pregnancy the coexistence of gestational hypertension and fetal growth restriction identifies preeclampsia with no need for other signs of maternal organ impairment. While early-onset fetal growth restriction and preeclampsia are often strictly associated, such association becomes looser in the late preterm and term periods. The incidence of preeclampsia decreases dramatically from early preterm fetal growth restriction (39-43%) to late preterm fetal growth restriction (9-32%) and finally to term fetal growth restriction (4-7%). Different placental and cardiovascular mechanism underlie this trend: isolated fetal growth restriction has less frequent placental vascular lesions than fetal growth restriction associated with preeclampsia; moreover, late preterm and term fetal growth restriction show different patterns of maternal cardiac output and peripheral vascular resistance in comparison with preeclampsia. Consequently, current strategies for first trimester screening of placental dysfunction, originally implemented for preeclampsia, do not perform well for late-onset fetal growth restriction: the sensitivity of first trimester combined screening for small-for-gestational age newborns delivered at less than 32 weeks is 56-63%, and progressively decreases for those delivered at 32-36 weeks (43-48%) or at term (21-26%). Moreover, while the test is more sensitive for small-for-gestational age associated with preeclampsia at any gestational age, its sensitivity is much lower for small-for-gestational age without preeclampsia at 32-36 weeks (31-37%) or at term (19-23%).

Early delivery or expectant management for late preterm preeclampsia: A meta-analysis of randomized controlled trials.

Currently, there is no consensus regarding the timing of delivery in women with non-severe preeclampsia at the late preterm period. The aim of the present meta-analysis is to compare expectant management with immediate delivery in pregnant women with preeclampsia between 34+0 and 36+6 gestational weeks, in terms of maternal and neonatal outcomes. A search was conducted until October 1, 2020 and eligible studies were identified in MEDLINE, Scopus, Cochrane Central Register of Controlled Trials (Central), the US Registry of clinical trials (www.clinicaltrials.gov), and sources of gray literature without limitations concerning the publication dates and languages. Randomized controlled trials, comparing planned delivery vs expectant management in women with preeclampsia at 34-37weeks were included. The primary outcomes were neonatal intensive care unit (NICU) admission and progression to eclampsia. Secondary outcomes were HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome, severe preeclampsia, composite adverse maternal outcome (defined by the presence of any of the potential preeclampsia-related complications, ranging from severe hypertension to maternal death), neonatal respiratory disease, and respiratory distress syndrome. Relative risks (RRs) and mean differences with 95% CI were used for the estimation of the effect sizes; the quality of the evidence was assessed per GRADE guidelines. The electronic search yielded 10721 potential studies, of which six were fully reviewed and three (1773 participants) were included in the meta-analysis. Immediate delivery increased the risk for NICU admission, (RR 1.23, 95% CI 1.05-1.45) and decreased the risk for the composite adverse maternal outcome (RR 0.86, 95% CI 0.78-0.93). There were no differences for eclampsia (RR 0.55, 95% CI 0.16-1.85), HELLP syndrome (RR 0.58, 95% CI 0.25-1.33), severe preeclampsia (RR 0.27, 95% CI 0.02-3.52), respiratory disease of neonate (RR 1.04, 95% CI 0.75-1.44), and respiratory distress syndrome (RR 2.3, 95% CI 0.73-7.25). Immediate delivery of women with non-severe preeclampsia at the period of late prematurity decreases the risk of a composite adverse maternal outcome by 14%, at the cost of an increase in NICU admissions by 23%. The overall quality of the evidence for these outcomes is high, indicating a high degree of certainty for the results.