Neonatal outcomes of extremely preterm infants exposed to maternal hypertension and cigarette smoking.

OBJECTIVE: To study the outcomes of extremely preterm infants of hypertensive mothers who smoke. STUDY DESIGN: This retrospective cohort study included infants born between 2003 and 2012 at <29 weeks' gestation and admitted to neonatal intensive care units participating in the Canadian Neonatal Network. Infants were divided into four mutually exclusive groups. Infants of hypertensive mothers who smoked; infants of hypertensive, non-smoking mothers; infants of normotensive mothers who smoked; and infants of normotensive, non-smoking mothers. Using infants of normotensive, non-smoking mothers as the reference group, neonatal outcomes were compared between the groups. Adjusted odds ratios (AORs) and 95% confidence intervals (CIs) were calculated using univariate and multivariate regression analysis. RESULTS: Of the 12,307 eligible infants, 172 had hypertensive mothers who smoked, 1689 had hypertensive non-smoking mothers, 1535 had normotensive mothers who smoked, and 8911 had normotensive non-smoking mothers. Compared to infants of normotensive non-smoking mothers, infants of hypertensive mothers, regardless of smoking status, had higher odds of developing bronchopulmonary dysplasia (AORs of smokers 1.62; 95% CI 1.12-2.35 and of non-smokers 1.43; 95% CI 1.24-1.64). There was no difference in the odds of mortality and retinopathy of prematurity stage ≥3 between the groups. Infants of hypertensive, non-smoking mothers had decreased odds of intraventricular hemorrhage >grade 2 and higher odds of necrotizing enterocolitis. There was decreased odds of hypertension if the mother was a smoker (AOR 0.71; 95% CI 0.59-0.85). CONCLUSION: Maternal hypertension is associated with increased rates of bronchopulmonary dysplasia, irrespective of smoking status.

CO(2) inhalation as a treatment for apnea of prematurity: a randomized double-blind controlled trial.

OBJECTIVE: To compare the effect of prolonged inhalation of a low concentration of CO(2) with theophylline for the treatment of apnea of prematurity. STUDY DESIGN: Prospective, randomized, double-blind controlled trial of 87 preterm infants with apnea of prematurity (27-32 weeks' gestational age) assigned to either theophylline plus 0.5 L/min of room air via nasal prongs or placebo plus 0.5 L/min with CO(2) (about 1% inhaled) by nasal prongs for 3 days. RESULTS: Apnea time significantly decreased in the theophylline group from 189±33 s/h (control) to 57±11, 50±9, and 61±13 (days 1-3) (P=.0001) and in the CO(2) group from 183±44 (control) to 101±26, 105±29, and 94±26 s/h (days 1-3) (P=.03). Seven infants in the CO(2) group but none in the theophylline group failed to complete the study due to severe apneas (P=.003). CONCLUSIONS: Because theophylline was more effective in reducing the number and severity of apneas, inhalation of low concentration of CO(2), as used in the present study, cannot be considered as an alternative to theophylline in the treatment of apnea of prematurity. The less effectiveness of CO(2) treatment may have been related to the variability of the delivery of CO(2).

Prostaglandins are responsible for the inhibition of breathing observed with a placental extract in fetal sheep.

We have previously observed that the infusion of a placental extract inhibits breathing movements in fetal sheep, suggesting that a placental factor may be responsible for the inhibition of fetal breathing. Our preliminary results suggested that a small peptide or a substance bound to a peptide was likely responsible for this inhibition. Since prostaglandins are found in high concentrations in the placenta, it is possible that they may be responsible for the inhibition of breathing observed with the placental extract. We hypothesized that if prostaglandins were the active factors in the placental extract, then inhibition of the production of placental prostaglandins should eliminate the activity of the extract. We infused untreated and indomethacin/ASA-treated placental extracts into the carotid artery of eight chronically instrumented fetal sheep continuously over 3 h. The concentration of all prostaglandins measured in the untreated placental extracts were significantly higher than in the indomethacin/ASA-treated extracts. Only the infusion of the untreated placental extract induced a significant decreased in the incidence of fetal breathing. Fetal plasma prostaglandins increased significantly only with the infusion of the untreated placental extracts. These findings suggest that the inhibition of breathing observed with the placental extract is likely related to prostaglandins.