Oral Presentation Society of Obstetric Medicine of Australia and New Zealand and Australasian Diabetes in Pregnancy Society Joint Scientific Meeting 2017

Predictors of lower vitamin D status in pregnant women with asthma and its association with preeclampsia (#61)

Megan E Jensen 1 2 , Peter G Gibson 3 , Carlos A Camargo Jr 4 , Vanessa E Murphy 2
  1. HMRI, University of Newcastle, Callaghan, NSW, Australia
  2. Priority Research Centre Grow Up Well, University of Newcastle and Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
  3. Priority Research Centre for Healthy Lungs, University of Newcastle and Hunter Medical Research Institute, New Lambton Heights, NSW, Australia
  4. Department of Emergency Medicine , Massachusetts General Hospital, Boston, MA, USA

Circulating 25-hydroxy-vitamin D [25(OH)D] <75nmol/L is common in pregnant women with asthma and associated with worse infant respiratory outcomes. In women with asthma, who are at increased risk of adverse perinatal outcomes, this study aimed to: (i) examine the determinants of 25(OH)D levels during pregnancy; and (ii) examine whether low vitamin D is associated with poor perinatal outcomes.

In 103 pregnant women with asthma, recruited from the John Hunter Hospital NSW Australia, serum 25(OH)D was measured at 17 and 36 weeks gestation, using enzyme-linked immunosorbent assay. Body mass index (BMI), gestational weight gain (GWG), asthma outcomes, and perinatal outcomes were recorded. Women were split into two groups: 25(OH)D <75nmol/L at both time-points vs. ≥75nmol/L at one or both time-points.

Backward stepwise regression modelled determinants of baseline and change (Δ) in 25(OH)D. Controlling for season, obesity (β=-12.9, p=0.008) was a significant determinant of baseline 25(OH)D (Adj-R2=0.12, p=0.005); ICS use was not (β=7.4, p=0.09). Baseline obesity (β=9.1, p=0.047), GWG above recommendations (β=-8.0, p=0.04), and season (Winter β=14.2, p=0.004; Spring β=17.4, p=0.002) were significant predictors of Δ25(OH)D (Adj-R2=0.39, p<0.001), controlling for ethnicity; exacerbations during pregnancy were not (β=-4.9, p=0.18).

Fifty-eight women (56%) had 25(OH)D levels <75nmol/L at both time-points. The incidence of preeclampsia was significantly greater in the persistently <75nmol/L group vs. those with higher vitamin D status: 8.6% (n=5) vs. 0%, p=0.04. Infant perinatal outcomes tended to be higher in the <75nmol/L group, but weren’t statistically significant: NICU admission (10.5% vs. 4.4%, p=0.26) and respiratory distress (10.5% vs. 2.2%, p=0.10).

In women with asthma, obesity and excessive GWG were significant modifiable determinants of baseline 25(OH)D and Δ25(OH)D during pregnancy. Importantly, vitamin D status may influence preeclampsia, a major complication in pregnancy. These data highlight the need for nutritional management in prenatal and antenatal care and requires further investigation in a larger cohort.