Body mass index and vaccine responses following influenza vaccination during pregnancy.

BACKGROUND AND AIMS: Influenza vaccination is recommended by the World Health Organisation for pregnant women, offering the dual benefit of protecting pregnant women and their newborn infants against influenza infection. Various factors can influence vaccine immunogenicity, with obesity being one factor implicated in varied responses. This study aimed to investigate the impact of body mass index (BMI) on vaccine responses following influenza vaccination during pregnancy. METHODS: Pregnant women attending the Women's and Children's Hospital in South Australia during 2014-2016 were invited to participate. Participant's clinical and demographic factors were recorded prior to administration of licensed seasonal influenza vaccination. Blood samples were collected before and one month post-vaccination to measure antibody responses by haemagglutination inhibition (HI) assay. Seroprotection was defined as a post-vaccination HI titre ≥ 1:40. Regression models assessed associations with failure to achieve seroprotective antibodies to H1, H3, and B influenza strains. RESULTS: A total of 96 women were enrolled in the study at a median gestation of 22 weeks with a BMI range of 18-49 kg/m2. Paired sera samples were available for 90/96 (94%). Most pregnant women (72/90, 80%) demonstrated seroprotective antibody titres to all three influenza vaccine antigens (A(H1N1)pdm09, A(H3N2), B/Yamagata) following vaccination. Compared with women with BMI < 30 kg/m2, those with high BMI were less likely to fail to achieve seroprotective antibodies, however this was not statistically significant (RR 0.42, 95% CI 0.11-1.68; p = 0.22). A greater proportion of women vaccinated during their second (47/53, 93%) or third trimester (18/25, 72%) demonstrated seroprotection to all three vaccine antigens following vaccination compared with women vaccinated during their first trimester (7/12, 58%). CONCLUSION: High BMI did not impair seroprotection levels following influenza vaccination in pregnant women. Gestation at vaccination may be an important consideration for optimising vaccine protection for pregnant women and their newborns. Further assessment of first trimester influenza vaccine responses is warranted.

Promoting early expression of breast milk in mothers of preterm infants in a neonatal unit: a best practice implementation project.

OBJECTIVES: The aim of this implementation project was to optimize lactation success in mothers of preterm infants by ensuring early (as soon as possible and within six hours) and frequent (eight to 12 times/day) milk expression. INTRODUCTION: Evidence suggests that breast milk improves enteral feeding tolerance and neurodevelopmental outcomes and decreases the risk of necrotising enterocolitis and late onset sepsis in preterm infants. It is widely accepted that breast milk expression should commence as soon as possible and within six hours of delivery. RESULTS: Following implementation of the breast milk expression information pack and staff education program, compliance to clinical guideline recommendations improved considerably. An increase from 5/20 (25%) to 17/20 (85%) of women expressing milk within six hours of delivery was observed. The average expression times also increased: from 2.6 (2.0) to 6.1 (2.7) times in the first 24 hours and from 4.6 (1.7) to 7.8 (1.7) times between 24-48 hours. The compliance rate for milk expression within six hours of delivery and expression of eight to 12 times daily in the first 48 hours increased from 1/20 (5%) at baseline to 10/20 (50%) in the follow-up audit. CONCLUSION: The implementation of the breast milk information pack and staff education led to improvements in the milk expression practices of mothers who had preterm infants. As a result of this project, the information packs are now routinely given to all women at risk of delivering preterm or who have babies in the neonatal unit. Further audits will be undertaken in the future to determine sustainability of practice changes.

Effect of body position changes on postprandial gastroesophageal reflux and gastric emptying in the healthy premature neonate.

OBJECTIVE: To identify a body-positioning regimen that promotes gastric emptying (GE) and reduces gastroesophageal reflux (GER) by changing body position 1 hour after feeding. STUDY DESIGN: Ten healthy preterm infants (7 male; mean postmenstrual age, 36 weeks [range, 33 to 38 weeks]) were monitored with combined esophageal impedance-manometry. Infants were positioned in the left lateral position (LLP) or right lateral position (RLP) and then gavage-fed. After 1 hour, the position was changed to the opposite side. Subsequently, all infants were restudied with the order of positioning reversed. RESULTS: There was more liquid GER in the RLP than in the LLP (median, 9.5 [range, 6.0 to 22.0] vs 2.0 [range, 0.0 to 5.0] episodes/hour; P = .002). In the RLP-first protocol, the number of liquid GER episodes per hour decreased significantly after position change (first postprandial hour [RLP], 5.5 [2.0 to 13.0] vs second postprandial hour [LLP], 0.0 [0.0 to 1.0]; P = .002). GE was faster in the RLP-first protocol than in the LLP-first protocol (37.0 +/- 21.1 vs 61.2 +/- 24.8 minutes; P = .006). CONCLUSIONS: A strategy of right lateral positioning for the first postprandial hour with a position change to the left thereafter promotes GE and reduces liquid GER in the late postprandial period and may prove to be a simple therapeutic approach for infants with GER disease.

Paradoxical impact of body positioning on gastroesophageal reflux and gastric emptying in the premature neonate.

OBJECTIVES: To combine manometry and impedance to characterize the mechanisms of gastroesophageal reflux (GER) and to explore their relation to the rate of gastric emptying (GE) and body position. STUDY DESIGN: Ten healthy preterm infants (35 to 37 weeks' postmenstrual age) were studied with the use of a micromanometric/impedance assembly. Episodes of GER were identified by impedance, and the mechanism(s) of GER triggering and GER clearance were characterized. GE was determined with a C13Na-octanoate breath test. RESULTS: Gastroesophageal reflux episodes (n=89) were recorded, consisting of 74% liquid, 14% gas, and 12% mixed. Transient lower esophageal sphincter relaxation (TLESR) was the predominant mechanism of reflux, triggering 83% of GER. Of 92 TLESRs recorded, 27% were not associated with reflux. Infants studied in the right lateral position had significantly (P <.01) more GER, a higher proportion of liquid GER (P <.05), and faster GE (P <.005) when compared with infants studied in the left lateral position. CONCLUSIONS: In healthy preterm infants, GER is predominantly liquid in nature. Right-side positioning is associated with increased triggering of TLESR and GER despite accelerating GE.