Sickle Cell Disease in pregnancy: a retrospective case control study in a London teaching hospital
Tasneem Singhal, Sophie Eleanor Kay, Jo Howard, Susan Robinson, Eugene Oteng-Ntim
Sickle Cell Disease (SCD) in pregnancy is associated with adverse maternal and fetal outcomes, but their incidence varies in different hospital settings. This study evaluates the incidence of maternal and fetal complications in pregnancies in women with SCD at a tertiary referral healthcare centre in London. It is the first sickle cell disease and pregnancy study to use case matched control comparison with the advantage of minimizing bias.
Data was collected on all pregnancies in women with SCD between 2001 and 2008. There were a total of 102 pregnancies over this time. Data included gestation, obstetric problems, analgesia, interventions performed, delivery method, baby weight, Apgar scores and maternal blood loss..
These 102 pregnancies were then individually case-matched to a control group of ‘normal’ pregnancies via a series of variables known to influence the outcome of delivery (i.e. age at delivery, gestation, number of previous pregnancies and ethnicity) that delivered within the study period. For the basis of this study a ‘normal’ pregnancy was defined as one where the mother did not have SCD. There were 39,673 eligible patients and matching was done by hand. At each stage of the comparison, the non-matching samples would be discarded for that certain SCD case, leaving us with 102 matched patients. Ethnicity was classified according to the Office of National Statistics classification. Maternal and fetal information was collected on these women and entered into the database, and the data on the SCD and control populations was compared. A ‘p’ value of p≤0.05 was considered significant, and was calculated using p distribution tables.
6.7% of women with SCD had sickle cell crises ante-nataly and they spent a mean of 8.0 days in hospital compared to the control group, which spent a mean of 3.9 days. Blood transfusion in pregnancy was more common in the SCD group, being required in 34.3% of women, compared with 2.0% of women in the non-SCD group. The incidence of preeclampsia was significantly higher in women with SCD: 7.8% versus 0%. Emergency Caesarean sections (CS) was the most common mode of delivery in women with SCD, 43.0% compared with 26.4% in the control group. There was no significant difference between the mean birth weights of the categories (p=0.20) or in IUGR in the SCD group with 3 pregnancies affected compared with 1 in the control group. There was no statistically significant difference in the means of Apgar scores between SCD and non-SCD group.
We have shown that whilst our maternal and fetal complications rates in pregnant women with SCD are better than those previously reported, which we suggest is due to improved medical care in a centre with a multidisciplinary team approach to obstetric care; there is still an increase in maternal complications when compared with matched case controls. Treatment of SCD has progressed in recent years to allow for more women to live to childbearing age. With appropriate knowledge and by following guidelines for its management it may be possible to decrease the complications of a SCD pregnancy