Rationale for review Young adults of childbearing age and pregnant women are travelling more frequently to tropical areas, exposing them to specific arboviral infections such as dengue, zika and chikungunya viruses, which may impact ongoing and future pregnancies. In this narrative review, we analyse their potential consequences on pregnancy outcomes and discuss current travel recommendations. Main findings Dengue virus may be associated with severe maternal complications, particularly post-partum haemorrhage. Its association with adverse fetal outcomes remains unclear, but prematurity, growth retardation and stillbirths may occur, particularly in cases of severe maternal infection. Zika virus is a teratogenic infectious agent associated with severe brain lesions, with similar risks to other well-known TORCH pathogens. Implications of chikungunya virus in pregnancy are mostly related to intrapartum transmission that may be associated with severe neonatal infections and long-term morbidity. Travel recommendations Few agencies provide specific travel recommendations for travelling pregnant patients or couples trying to conceive and discrepancies exist, particularly regarding Zika virus prevention. The risks significantly depend on epidemiological factors that may be difficult to predict. Prevention relies principally on mosquito control measures. Couples trying to conceive and pregnant women should receive adequate information about the potential risks. It seems reasonable to advise pregnant women to avoid unnecessary travel to Aedes spp. endemic regions. The current rationale to avoid travel and delay conception is debatable in the absence of any epidemic. Post-travel laboratory testing should be reserved for symptomatic patients.

Zika virus (ZIKV), a neurotropic single-stranded RNA flavivirus, remains an important cause of congenital infection, fetal microcephaly, and Guillain-Barré syndrome in populations where ZIKV has adapted to a nexus involving the Aedes mosquitoes and humans. To date, outbreaks of ZIKV have occurred in Africa, Southeast Asia, the Pacific islands, the Americas, and the Caribbean. Emerging evidence, however, suggests that the virus also has the potential to cause infections in Europe, where autochtonous transmission of the virus has been identified. This review focuses on evolving ZIKV epidemiology, modes of transmission and host-virus interactions. The clinical manifestations, diagnostic issues relating to cross-reactivity to the dengue flavivirus and concerns surrounding ZIKV infection in pregnancy are discussed. In the last section, current challenges in treatment and prevention are outlined.

Introduction Corpus callosum agenesis (ACC) is frequently diagnosed during fetal life; its prognosis depends also on additional anomalies. The additional value of fetal magnetic resonance imaging (MRI) in fetuses with “isolated” complete (cACC) and partial (pACC) agenesis of the corpus callosum on ultrasound is still debated. Material and methods We performed a systematic literature review and meta‐analysis including fetuses with a prenatal diagnosis of cACC and pACC without associated structural anomalies on ultrasound, undergoing fetal MRI. The primary outcome was the rate of additional anomalies detected at fetal MRI. Further analyses assessed the effect of type of ultrasound assessment (neurosonography vs standard axial assessment), gestational age at fetal MRI and rate of postnatally detected brain anomalies. Random‐effect meta‐analyses of proportions were used to analyze the data. Results Fourteen studies (798 fetuses) were included. In cases with isolated cACC, 10.9% (95% CI 4.1‐20.6) and 4.3% (95% CI 1.4‐8.8) additional anomalies were detected by fetal MRI and postnatally, respectively. Stratifying according to the type of ultrasound assessment, the rate of associated anomalies detected only on fetal MRI was 5.7% (95% CI 0.5‐16.0) with dedicated neurosonography and 18.5% (95% CI 7.8‐32.4) with a standard axial assessment. In fetuses with isolated pACC, 13.4% (95% CI 4.0‐27.0) and 16.2% (95% CI 5.9‐30.3) additional anomalies were detected by fetal MRI or postnatally, respectively. Stratifying according to the type of ultrasound assessment, the rate of associated anomalies detected only on fetal MRI was 11.4% (95% CI 2.7‐25.0) when dedicated neurosonography was performed. Cortical and posterior fossa anomalies represented the most common anomalies missed at ultrasound with both cACC and pACC. Due to the very small number of included cases, stratification according to early (<24 weeks of gestation) and late (>24 weeks) fetal MRI could not be done for either cACC or pACC. Conclusions The rate of associated anomalies detected exclusively at fetal MRI in isolated ACC undergoing neurosonography is lower than previously reported. Cortical and posterior fossa anomalies are among the most common anomalies detected exclusively at MRI, thus confirming the crucial role of fetal MRI in determining the prognosis of these fetuses. However, some anomalies still go undetected prenatally and this should be stressed during parental counseling.

Objectives To assess the natural evolution of the size of the fetal lateral ventricles throughout pregnancy in fetuses with callosal anomalies. Methods Cases of fetal callosal anomalies were retrospectively classified as isolated or complex based on the presence of other structural or genetic anomalies. Longitudinal ultrasound studies were reviewed, and postnatal outcomes were retrieved for isolated cases. Results In 135 fetuses, those who first presented after 24 weeks’ gestation were more likely to have ventriculomegaly (n = 58 of 68 [85%]) than those who presented before 24 weeks (n = 39 of 67 [58%]; P < .001). In 79 cases that had longitudinal follow‐up, the mean increase in ventricular width was 0.6 mm/wk, without a significant difference between isolated and complex cases (mean ± SD, 0.6 ± 1.5 versus 0.6 ± 1.1 mm; P = .45). Conclusions Callosal anomalies are associated with progressive ventriculomegaly on prenatal ultrasound imaging, without a difference between isolated and complex anomalies. This feature should be considered part of the disease spectrum. The consequence of progressive ventriculomegaly on the long‐term neurodevelopmental outcome is still unknown, and further studies should be aimed at obtaining long‐term follow‐up of these cases.

Zika virus (ZIKV) recently emerged as a global public health emergency of international concern. ZIKV is responsible for severe neurological complications in adults and infection during pregnancy and can lead to congenital Zika syndrome. There is no licensed vaccine or drug to prevent or treat ZIKV infection. Areas covered: The aim of this article is to provide an overview and update of the progress of research on anti-ZIKV vaccine and medications until the end of 2017, with a special emphasis on drugs that can be used during pregnancy. Expert commentary: Development of new vaccines and drugs is challenging and several points particular to ZIKV infections augment this difficulty: (1) Cross-reactions between ZIKV and other flaviviruses, the impact of ZIKV vaccination on subsequent flavivirus infections, and vice-versa, is unknown, (2) Drugs against ZIKV should be safe in pregnant women, and (3) Evaluation of the efficacy of vaccine and drugs against ZIKV in clinical trials phase II-IV will be complicated due to the decline of ZIKV circulation.

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In this multicentre cohort study, we evaluated the risks of maternal ZIKV infections and adverse pregnancy outcomes among exposed travellers compared to women living in areas with ZIKV circulation (residents). The risk of maternal infection was lower among travellers compared to residents: 25.0% (n = 36/144) versus 42.9% (n = 309/721); aRR 0.6; 95%CI 0.5–0.8. Risk factors associated with maternal infection among travellers were travelling during the epidemic period (i.e., June 2015 to December 2016) (aOR 29.4; 95%CI 3.7-228.1), travelling to the Caribbean Islands (aOR 3.2; 95%CI 1.2-8.7) and stay duration >2 weeks (aOR 8.7; 95%CI 1.1–71.5). Adverse pregnancy outcomes were observed in 8.3% (n = 3/36) of infected travellers and 12.7% (n = 39/309) of infected residents. Overall, the risk of maternal infections is lower among travellers compared to residents and related to the presence of ongoing outbreaks and stay duration, with stays <2 weeks associated with minimal risk in the absence of ongoing outbreaks.