Split-week gestational age model provides valuable information on outcomes in extremely preterm infants

Survival outcomes among periviable infants: a systematic review and meta-analysis comparing different income countries and time periods

Background

Periviable infants are a highly vulnerable neonatal group, and their survival rates are considerably affected by patient-, caregiver-, and institution-level factors, exhibiting wide variability across different income countries and time periods. This study aims to systematically review the literature on the survival rates of periviable infants and compare rates among countries with varied income levels and across different time periods.

Methods

Comprehensive searches were conducted across MEDLINE, Embase, CENTRAL, and Web of Science. Cohort studies reporting survival outcomes by gestational age (GA) for periviable infants born between 22 + 0 and 25 + 6 weeks of gestation were considered. Paired reviewers independently extracted data and assessed the risk of bias and quality of evidence. Data pooling was achieved using random-effects meta-analyses.

Results

Sixty-nine studies from 25 countries were included, covering 56,526 live births and 59,104 neonatal intensive care unit (NICU) admissions. Survival rates for infants born between 22 and 25 weeks of GA ranged from 7% (95% CI 5-10; 22 studies, n = 5,658; low certainty) to 68% (95% CI 63-72; 35 studies, n = 21,897; low certainty) when calculated using live births as the denominator, and from 30% (95% CI 25-36; 31 studies, n = 3,991; very low certainty) to 74% (95% CI 70-77; 48 studies, n = 17,664, very low certainty) for those admitted to NICUs. The survival rates improved over the two decades studied; however, stark contrasts were evident across countries with varying income levels.

Conclusion

Although the survival rates for periviable infants have improved over the past two decades, substantial disparities persist across different economic settings, highlighting global inequalities in perinatal health. Continued research and collaborative efforts are imperative to further improve the global survival and long-term outcomes of periviable infants, especially those in Low- and Middle-Income Countries.

Systematic review registration

PROSPERO, CRD42022376367, available from: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022376367.

A Growing Dilemma: Antenatal Corticosteroids and Long-Term Consequences

OBJECTIVE

A single course of synthetic antenatal corticosteroids is standard care for women considered to be at risk for preterm birth before 34 weeks of gestation. While the intended target is the fetal lung, the fetal brain contains remarkably high levels of glucocorticoid receptors in structures critical in the regulation of behavior and endocrine function. Negative programming signals may occur which can lead to permanent maladaptive changes and predispose the infant/child to an increased risk in physical, mental, and developmental disorders.

METHODS

Framed around these areas of concerns for physical, mental, and developmental disorders, this narrative review drew on studies (animal and clinical), evaluating the long-term effects of antenatal corticosteroids to present the case that a more targeted approach to the use of antenatal corticosteroids for the betterment of the fetus urgently needed.

RESULTS

Studies raised concerns about the potential negative long-term consequences, especially for the exposed fetus who was born beyond the period of the greatest benefit from antenatal corticosteroids. The long-term consequences are more subtle in nature and usually manifest later in life, often beyond the scope of most clinical trials.

CONCLUSION

Continued research is needed to identify sufficient safety data, both short term and long term. Caution in the use of antenatal corticosteroids should be exercised while additional work is undertaken to optimize dosing strategies and better identify women at risk of preterm birth prior to administration of antenatal corticosteroids.

KEY POINTS

· A single-course ACS is a remarkable therapy with substantial benefits.. · There is a potential of long-term neurodevelopmental consequences in the ACS-exposed fetus.. · There is a need to improve dosing strategies and identification of appropriate at risk women..

Does a Split-Week Gestational Age Model Provide Valuable Information on Neurodevelopmental Outcomes in Extremely Preterm Infants?

Our primary objective for this follow-up study was to compare the neurodevelopmental outcomes of a surviving cohort of infants using a split-week gestational model (early versus late) gestational age (GA) and the standard completed GA categorization. Neurodevelopmental outcomes using a split-week GA model defined as early (X, 0–3) and late (X, 4–6), with X being 23–26 weeks GA, were compared to outcomes using completed weeks GA. In total, 1012 infants were included in the study. Statistically significant differences were noted in outcomes between the early and late split of the gestational week at 23 weeks (early vs. late), with 13.3% vs. 54.5% for no neurodevelopmental impairment, and 53.3% vs. 22.7% for significant impairment (p = 0.034), respectively. There were no differences seen in the split week model for 24, 25, and 26 weeks. A trend towards improved neurodevelopmental outcomes was seen with each increasing gestation week. The split-week model did not provide additional information for pregnancies and infants between 24 and 26 weeks gestation. It did, however, provide information for counsel for infants at 23 weeks gestation, showing benefits in the late versus early half of the week.

Gestation-Based Viability-Difficult Decisions with Far-Reaching Consequences

Most clinicians rely on outcome data based on completed weeks of gestational of fetal maturity for antenatal and postnatal counseling, especially for preterm infants born at the margins of viability. Contemporary estimation of gestational maturity, based on ultrasounds, relies on the use of first-trimester scans, which offer an accuracy of ±3-7 days, and depend on the timing of the scans and the measurements used in the calculations. Most published literature on the outcomes of babies born prematurely have reported on short- and long-term outcomes based on completed gestational weeks of fetal maturity at birth. These outcome data change significantly from one week to the next, especially around the margin of gestational viability. With a change in approach solely from decisions based on survival, to disability-free survival and long-term functional outcomes, the complexity of the parental and care provider's decision-making in the perinatal and postnatal period for babies born at less than 25 weeks gestation remains challenging. While sustaining life following birth at the margins of viability remains our priority-identifying and mitigating risks associated with extremely preterm birth begins in the perinatal period. The challenge of supporting the normal maturation of these babies postnatally has far-reaching consequences and depends on our ability to sustain life while optimizing growth, nutrition, and the repair of organs compromised by the consequences of preterm birth. This article aims to explore the ethical and medical complexities of contemporary decision-making in the perinatal and postnatal periods. We identify gaps in our current knowledge of this topic and suggest areas for future research, while offering a perspective for future collaborative decision-making and care for babies born at the margins of viability.