Interpretation
Previous studies have demonstrated significant reductions in pulmonary
functional reserves in SCD 2,4. Also, existing data
show strong associations between reduction in FEV1%
predicted and SCD-related morbidity and mortality23–25. What remains unclear is whether reduction in
pulmonary function in pregnant women with SCD is associated with adverse
pregnancy outcomes. The results of our study suggest that in pregnant
women with SCD, low FEV1% predicted is associated with
an increased risk of fetal death
In the general population, low FEV1% predicted or
decline in FEV1 has been shown to be associated with
mortality 21,24–28. Also in the general population,
FEV1% predicted is a known robust predictor of sudden
cardiac death, with the relationship independent of cardiac function26,28. In addition our team has previously
demonstrated that low FEV1% predicted is a predictor of
earlier death in young adults with SCD and future ACS episodes27.
Prior studies have indicated that low FEV1% predicted
during pregnancy is associated with adverse perinatal outcome in
pregnant women with cystic fibrosis 21,22,29,30;
however, the biological basis for this association has not been
elucidated. Reynaud et al . have reported that pregnancy in women
with cystic fibrosis and poor pulmonary function has a negative impact
on fetal growth 21. Other retrospective analyses of
pregnancies in women with cystic fibrosis have further highlighted low
maternal baseline FEV1% predicted as a predictor of
premature delivery, LBW and fetal death 22,29,30.
These findings in pregnant women with cystic fibrosis lend credence to
the biological plausibility that observed association between lower
FEV1% predicted and fetal death in SCD.
We found no significant association between low maternal
FEV1% predicted and adverse maternal outcomes including
ACS, acute painful episodes and maternal deaths. Although we found no
statistical difference between the rates of acute painful episodes, ACS,
and deaths in women with baseline FEV1% predicted ≥ 65
and those with FEV1% predicted < 65, the mean
events per patient year for acute pain episodes and ACS, and maternal
mortality were higher (33%, 150%, and 370% respectively) in the group
with FEV1% predicted < 65, compared to the
group with FEV1% predicted ≥ 65. The lack of
statistically significant difference in our study may be due to limited
power or the natural short follow-up period during pregnancy. These
limitations can be overcome with larger multi-center prospective
studies.