346 - Thrombocytopenia and neonatal outcomes among extremely premature infants exposed to maternal hypertension

Poster Number: 346
Publication Number: 346.122

Joanne Delaney, McGill University Faculty of Medicine and Health Sciences, Montreal, PQ, Canada; Gabriela De Carvalho Nunes, McGill University Faculty of Medicine and Health Sciences, Montreal, PQ, Canada; Jessica simoneau, McGill University Faculty of Medicine and Health Sciences, Montreal, PQ, Canada; Catherine Goudie, McGill University Health Centre, Montreal, PQ, Canada; Gabriel Altit, McGill University Faculty of Medicine and Health Sciences, Montreal, PQ, Canada

Background: Maternal hypertensive disorders (MHD) are commonly encountered in pregnancy, and are associated with unfavourable neonatal outcomes such as intraventricular hemorrhage (IVH), bronchopulmonary dysplasia (BPD), and necrotizing enterocolitis (NEC), particularly among extremely premature neonates. Infants born to MHD also have higher incidences of hematologic abnormalities, including thrombocytopenia. The pathogenesis of thrombocytopenia in this setting is poorly understood, as is its association to these adverse outcomes.

Objective: In extreme preterm newborns, evaluate the association of exposure to MHD and postnatal platelet behaviour. As well, explore the association between platelet count and adverse outcomes.

Design/Methods: Retrospective cohort of infants born at < 29 weeks admitted to a level IV Neonatal Intensive Care Unit (NICU) between 2015 and 2019. Outcome data collected for each infant included rates of IVH (grade 3 or 4), BPD, NEC, and death, as well as frequency and volume of platelet transfusion. Hypothesized predictors for developing outcomes were platelet count at initial complete blood count (CBC), at 2 weeks of life, at 32 weeks and 36 weeks corrected age and at discharge. Odds of exposure to predictors for the adverse outcomes were compared between neonates born to mothers with MHD to those without. A mixed effect model with random slope/intercept was constructed to identify the association between MHD and platelet count trajectory during hospitalization.

Results: 298 extremely premature infants were included, 43 of whom were born to mothers with MHD. Infants exposed had a significantly higher incidence of thrombocytopenia compared to non-exposed (82% vs 31%, p < 0.001), and were more likely to have received platelet transfusions (76.4% vs 45%, p < 0.001), ), Table 1. Infants exposed to MHD had a higher incidence of BPD (74% vs 54%, p=0.02503), Table 2. Logistic regression analysis demonstrated an association between development of grade 3-4 IVH and platelet count on initial CBC (OR 0.94, p=0.01502) and CBC at 36 weeks of gestation (OR 0.99, p=0.02). An association was found between BPD and platelet count at 2 weeks of life (OR 0.96, p=0.02) and 36 weeks of gestation (OR 0.98, p=0.02). Mixed effect model (Table 3) showed an association between maternal hypertension and slower trajectory of platelet count recovery during admission (β =-94× 103/μL, p < 0.001).Conclusion(s): Extremely premature infants born to MHD have a higher incidence of thrombocytopenia and an altered trajectory of platelet recovery. This profile may contribute to the development of adverse outcomes such as IVH and BPD.
Table 1: Baseline Patient CharacteristicsExpressed as count (percent) and mean (standard deviation).
*Chi2, Fisher’s exact, Wilcoxon-Mann-Whitney and Student t tests were used to assess differences in categorical and continuous variables using StataSE.
Abbreviations: HTN (hypertensive disorder), SGA (small for gestational age, defined as birth weight < 10th percentile according to Fenton growth chart).
Table 2: OutcomesExpressed as count (percent) and mean (standard deviation).
*Chi2, Fisher’s exact, Wilcoxon-Mann-Whitney and Student t tests were used to assess differences in categorical and continuous variables using StataSE.
**Adjusted for maternal hypertension, antenatal steroids, gestational age at birth
Abbreviations: BPD (bronchopulmonary dysplasia defined as respiratory support or oxygen supplementation at 36 weeks post-menstrual age), IVH (intraventricular hemorrhage according to the Papile’s classification), mL/kg (milliliteres per kilogram of weight at the time of the transfusion), NEC (necrotizing enterocolitis defined as a stage 2 and above according to the Bell’s classification), PMA (post-menstrual age), PVL (periventricular leukomalacia), ROP (Retinopathy of prematurity stage 3 or more as defined by the International Classification for Retinopathy of Prematurity or requiring treatment with laser photocoagulation or intra-ocular injection of bevacizumab). Late onset sepsis defined by a positive bacterial or fungal culture in blood and/or cerebrospinal fluid beyond two days of life.