Effect of Coronavirus Disease-2019 on the Workload of Neonatologists

OBJECTIVE

To describe the impact of coronavirus disease-2019 (COVID-19) on the neonatology workforce, focusing on professional and domestic workloads.

STUDY DESIGN

We surveyed US neonatologists in December 2020 regarding the impact of COVID-19 on professional and domestic work during the pandemic. We estimated associations between changes in time spent on types of professional and domestic work and demographic variables with multivariable logistic regression analyses.

RESULTS

Two-thirds (67.6%) of the 758 participants were women. Higher proportions of women than men were in the younger age group (63.3% vs 29.3%), held no leadership position (61.4% vs 46.3%), had dependents at home (68.8% vs 56.3%), did not have a partner or other adult at home (10.6% vs 3.2%), and had an employed partner (88.1% vs 64.6%) (P < .01 for all). A higher proportion of women than men reported a decrease in time spent on scholarly work (35.0% vs 29.0%; P = .02) and career development (44.2% vs 34.9%; P < .01). A higher proportion of women than men reported spending more time caring for children (74.2% vs 55.8%; P < .01). Reduced time spent on career development was associated with younger age (aOR, 2.21; 95% CI, 1.20-4.08) and number of dependents (aOR, 1.21; 95% CI, 1.01-1.45). Women were more likely to report an increase in time spent time doing domestic work (aOR, 1.53; 95% CI, 1.07-2.19) and a reduction in time on self-care (aOR, 0.49; 95% CI, 0.29-0.81).

CONCLUSIONS

COVID-19 significantly impacts the neonatology workforce, disproportionately affecting younger, parent, and women physicians. Targeted interventions are needed to support postpandemic career recovery and advance physician contributions to the field.

Antibiotic Safety and Effectiveness in Premature Infants With Complicated Intraabdominal Infections

BACKGROUND

In premature infants, complicated intraabdominal infections (cIAIs) are a leading cause of morbidity and mortality. Although universally prescribed, the safety and effectiveness of commonly used antibiotic regimens have not been established in this population.

METHODS

Infants ≤33 weeks gestational age and <121 days postnatal age with cIAI were randomized to ≤10 days of ampicillin, gentamicin, and metronidazole (group 1); ampicillin, gentamicin, and clindamycin (group 2); or piperacillin-tazobactam and gentamicin (group 3) at doses stratified by postmenstrual age. Due to slow enrollment, a protocol amendment allowed eligible infants already receiving study regimens to enroll without randomization. The primary outcome was mortality within 30 days of study drug completion. Secondary outcomes included adverse events, outcomes of special interest, and therapeutic success (absence of death, negative cultures, and clinical cure score >4) 30 days after study drug completion.

RESULTS

One hundred eighty infants [128 randomized (R), 52 nonrandomized (NR)] were enrolled: 63 in group 1 (45 R, 18 NR), 47 in group 2 (41 R, 6 NR), and 70 in group 3 (42 R, 28 NR). Thirty-day mortality was 8%, 7%, and 9% in groups 1, 2, and 3, respectively. There were no differences in safety outcomes between antibiotic regimens. After adjusting for treatment group and gestational age, mortality rates through end of follow-up were 4.22 [95% confidence interval (CI): 1.39-12.13], 4.53 (95% CI: 1.21-15.50), and 4.07 (95% CI: 1.22-12.70) for groups 1, 2, and 3, respectively.

CONCLUSIONS

Each of the antibiotic regimens are safe in premature infants with cIAI.

CLINICAL TRIAL REGISTRATION

NCT0199499.

Fetal growth restriction is not associated with a reduced risk for bilateral spastic cerebral palsy in very-low-birthweight infants

OBJECTIVE

To evaluate the influence of confounding and sampling bias on the relationship between fetal growth restriction in a very-low-birthweight-defined cohort (VLBW, < or =1500 g) and bilateral spastic cerebral palsy (BSCP) at early school-age.

METHODS

Three hundred twenty-four of 407 long-term survivors of a regional cohort of VLBW newborns were followed until age 6 years. We categorized as small for gestational age (SGA) all infants whose birthweight Z-score was below -2 relative to published reference values. Uni- and multivariable logistic regression models were fit to estimate the risk of BSCP associated with SGA in the total sample, in subsamples defined by gestational age, and in a gestational age-matched case-control sample.

RESULTS

In the total sample, no child below 28 weeks was SGA, and no child above 32 weeks had an appropriate birthweight for gestational age (AGA). The prevalence of BSCP was 14% in AGA and 2% in SGA infants. In both uni- and multivariable logistic regression analyses of the total sample, SGA was associated with a prominently reduced risk of BSCP (odds ratios range from 0.1 to 0.2, all 95% confidence limits exclude 1.0). However, analyses performed in samples defined by different gestational age cutoffs (24--31 weeks, 28--31 weeks) and in a sample using three gestational age-matched controls per BSCP-case did not show a protection by growth restriction (odds ratios range from 0.8 to 2.2, all 95% confidence limits include 1.0).

CONCLUSIONS

In VLBW-defined samples, the apparent protective effect of SGA for BSCP can be explained, at least in part, by the highly skewed distribution of SGA over the available gestational age range. From this follows that study cohorts should be defined by gestational age and not by birthweight. In distorted samples like this one, even controlling for gestational age does not reduce the illusion of a reduced cerebral palsy risk for growth restricted infants. Only restriction of the sample by gestational age and/or matching for gestational age reveals the absence of this apparent protective effect.

Androgen regulation of signaling pathways in late fetal mouse lung development

During lung development there is tension between positive and negative regulators of fibroblast-epithelial communication controlling type II cell differentiation. A clinical consequence of imbalance of this tension is the increased risk for respiratory distress syndrome in male infants. We hypothesized that chronic intrauterine androgen exposure alters fetal lung fibroblast maturation by down-regulating epidermal growth factor receptor (EGF-R) activity and by up-regulating transforming growth factor-beta receptor (TGFbeta-R) activity, leading to an inhibition of surfactant protein B (SP-B) and -C (SP-C) gene expression in type II cells. We treated pregnant mice with dihydrotestosterone (DHT; 2 mg/day) or vehicle for 7 days, starting on gestational day 11. On day 18, EGF binding, EGF-R phosphorylation, TGFbeta-R binding, and TGFbeta1-induced cell proliferation were studied in sex-specific fibroblast cultures. SP-B and -C messenger RNA levels were measured in whole lungs. Chronic DHT treatment reduced both EGF binding (females to 78+/-8% and males to 65+/-9% of controls) and EGF-induced EGF-R phosphorylation. TGFbeta-R binding was increased (females to 173+/-39% and males to 280+/-64% of controls), and TGFbeta-induced cell proliferation was increased in female cells (231+/-57% of controls). SP-B and -C messenger RNA expression was reduced to 55+/-10% and 75+/-4%, respectively. We conclude that chronic DHT exposure beginning early in lung development alters the balance of growth factor signaling that regulates lung maturation.

Pulmonary function at school-age in surfactant-treated preterm infants

A follow-up study was conducted in 40 children who had been enrolled in a prospective randomized study of exogenous surfactant therapy for respiratory distress syndrome (RDS) (n = 22; S) or placebo (n = 18; P) to determine long-term pulmonary sequelae of surfactant treatment in premature infants with RDS. At follow-up, mean (SD) age was 6.63 (0.18) and 6.55 (0.23) years for S and P, respectively. Complete lung function tests (LFT) were attempted in all patients. Satisfactory data were obtained in 17/22 surfactant-treated and in 12/18 control children. There was no significant difference between groups for any of the parameters measured. Mean (SD) functional residual capacity (FRC) was 92% (16%) and 90% (21%) predicted, mean (SD) airway resistance (R(aw,exp)) was 122% (25%) and 127% (61%), and mean (SD) forced expiratory volume in 1 s (FEV1) was 104% (12%) and 99% (17%) predicted for S and P. Only maximal expiratory flow at 25% vital capacity (L/s) was significantly below the predicted range in S and P groups, with 74% (23%) and 77% (28%), respectively. To test bronchial hyperreactivity, a simple standardized running test was performed: 4 children in S and 5 in P showed a significant response as defined by clinical airway obstruction or changes in FEV1 and/or R(aw), with no significant difference between groups. Although we found no major abnormalities in lung function and no difference between S and P at early school-age, lack of cooperation during lung function tests makes further follow-up necessary.

Transforming growth factor beta 1 binding and receptor kinetics in fetal mouse lung fibroblasts

TGFbeta1 inhibits fetal lung maturation in vitro. As TGFbeta1 is present in fetal lung, mechanisms must exist to overcome this inhibition and allow late gestation maturation to progress. We studied the ontogeny of TGFbeta1 binding, and TGFbeta receptor kinetics and subtypes in primary cultures of fetal mouse lung fibroblasts from Day 16 to Day 18 of gestation. TGFbeta1 specific binding in fetal lung fibroblasts declined with advancing gestation. The decrease occurred earlier, and was more pronounced in female fibroblasts (50% decrease) than in the male fibroblasts (29% decrease). Dihydrotestosterone treatment of Day 18 female fibroblasts resulted in a dose-dependent increase in TGFbeta1 binding. Scatchard analysis revealed a decline in receptor number with advancing gestation (Day 16 female Bmax: 7.3 x 10(-16); Day 18 female Bmax: 5.5 x 10[-16]) whereas binding affinities remained constant. Affinity labeling followed by chemical cross-linking and autoradiography showed the three known TGFbeta receptor subtypes at both Days 16 and 18 of gestation. The relative abundance of nonsignaling Type III receptors in comparison to signaling Type II and Type I receptors was increased at Day 18 versus Day 16. Incorporation of [3H]thymidine into DNA after treatment with TGFbeta1 changed from Day 16 to Day 18, consistent with changes previously reported between fetal and adult lung fibroblasts. We conclude that as fetal mouse lung maturation progresses, TGFbeta receptor number decreases in fibroblasts, the relative proportion of nonsignaling versus signaling receptor types increases, and the response to TGFbeta1 stimulation changes. These changes may contribute to overcoming TGFbeta1 inhibition of lung maturation.

Regulation of the epidermal growth factor receptor in fetal rat lung fibroblasts during late gestation

Lung epithelial cell differentiation is predominantly regulated by mesenchymal-epithelial cell communication. We have previously shown that epidermal growth factor (EGF) positively influences this process, and that EGF receptor (EGF-R) binding in fetal rat lung fibroblasts peaks on d18-19 of gestation, just before the onset of augmented surfactant synthesis. This regulation of EGF-R in late gestation fetal lung fibroblasts may control the timing of mesenchymal-epithelial cell communication leading to surfactant synthesis. Hormones and growth factors exert positive and negative influences on lung development, but whether they regulate the EGF-R is unknown. We hypothesized that positive [EGF, cortisol, retinoic acid (RA)] and negative [transforming growth-factor-beta1 (TGF-beta1), dihydrotestosterone (DHT)] regulators of lung cell development regulate the EGF-R in the fetal lung. We studied EGF-R binding and protein abundance in sex-specific fetal rat lung fibroblasts cultured at d17, d19, and d21. EGF-R binding was significantly elevated after RA (both sexes d17 and d19, females d21) and after DHT (females d19) treatment. EGF and cortisol had minimal or inhibitory effects on EGF-R binding. Western blot analysis showed that the observed changes in EGF-R binding were associated with similar changes in EGF-R protein. We conclude that factors that affect lung maturation continue to regulate EGF-R in a developmental, sex-specific manner during late gestation.

Expression and activity of epidermal growth factor receptor in late fetal rat lung is cell- and sex-specific

Epidermal growth factor (EGF) augments late fetal lung maturation by advancing the ontogeny of fetal lung development and by stimulating surfactant synthesis. Previous studies have indicated that fibroblastalveolar epithelial cell communications mediate surfactant synthesis in the fetal lung and EGF acts through such a mechanism. We investigated the hypothesis that is differential activity and expression of the epidermal growth factor receptor (EGF-R) in fetal lung fibroblasts during the canalicular stage of lung development mediates EGF effects. To test this hypothesis, we examined fetal rat lung fibroblasts (FLFs) and type II cells of late gestation (canalicular and saccular stages; 17-22 days) by EGF-R binding techniques, SDS-PAGE, and Western blot analysis. Specific EGF binding increased 181% in day 18 female FLFs, with male FLFs exhibiting a similar increase on day 19. In contrast, specific EGF binding was low in type II cells, did not increase during late gestation, and there were no sex-specific differences. SDS-PAGE and Western blot analysis revealed a predominant 170-kDa EGF-R band in fibroblasts that increased with gestation (peak = 19 days), and was stronger in females. Immunoprecipitation of EGF-treated cells demonstrated the tyrosine kinase activity of the identified receptor. In contrast, type II cells showed minimal signal that did not increase until day 21 of gestation. We also examined whole fetal lung sections by immunohistochemistry to determine cell-specific expression of the EGF-R in vivo. Immunohistochemistry revealed specific EGF-R staining in columnar and cuboidal epithelia of small conducting airways and in mesenchyme of epithelial-mesenchymal borders (including subepithelial mesenchyme). In contrast, alveolar epithelia showed minimal staining, while subalveolar mesenchyme EGF-R staining peaked at day 19 of gestation. We conclude that cell-specific and sex-specific differences in EGF-R binding and EGF-R immunolocalization appears in the fetal lung at a developmental stage that is critical for alveolar epithelial cell differentiation. The results suggest a role for EGF-R activation in late fetal alveolar epithelial cell maturation, which is mediated through mesenchymal-epithelial cell communication.