Guest posting: Dr Ayesha Akram, Microbiology Registrar, Pathology North, NSW. 

Prematurity and low birth weight are important causes of neonatal death and despite increasing awareness of the importance of these adverse pregnancy outcomes, the causes remains unknown on many occasions. Dengue fever is endemic in many regions of the world especially in Southeast Asia and Oceania. With 390 million estimated dengue infections each year woman of reproductive age are also at increasing risk of symptomatic dengue infection.  Previously very little was known about the possible adverse effects of dengue infection during pregnancy.

Dengue during Pregnancy and adverse fetal outcomes: 2016 systemic review and meta-analysis attempted to estimate the increase in risk of four adverse fetal outcomes including miscarriage, stillbirth, preterm birth and low birth weight in women who had dengue infection during pregnancy.

16 studies were included in the systemic review and 8 in the meta-analysis. These studies were published from 1994 to 2014 from Cuba, Brazil, Columbia, Malaysia, India, Sri Lanka and Mexico. 6,071 pregnant women, 292 of whom were exposed to dengue during pregnancy were included in these studies. The prevalence of miscarriage associated with dengue infection during pregnancy ranged from 3.8% to 16% in different studies.  For miscarriage the odds ratio (OR) was 3.5 (95% CI 1·15–10·77, p=0·765) for women with dengue during pregnancy compared to unexposed pregnant women. Preterm birth and low birth weight were the most common adverse pregnancy outcomes. The OR for association with dengue was 1.71 (95% CI 1·06–2·76, p=0·058) for preterm labour and 1.41 (95% CI 0·90–2·21, p=0·543) for low birth weight. Meta-analysis was not done for stillbirth as this outcome was only one study with a comparison group. The crude relative risk for stillbirth was 6.7 (95% CI .1-21.3) for women with symptomatic dengue compared with women without dengue.

Despite limitations arising from inclusion of case series with small sample sizes,  an association was found between symptomatic dengue infection and adverse fetal outcomes. Further studies are required to confirm this association and, if confirmed,  close monitoring of pregnant women with dengue infection to reduce adverse foetal outcomes and including pregnant women as at high risk population for dengue control strategies will be required.

Reference

• Dengue during Pregnancy and adverse fetal outcomes: systemic review and meta-analysis. Lancet Infectious Diseases Volume 16, No. 7, p857–865.