Introduction Neonatal herpes can result from intrauterine, perinatal, and postnatal herpes simplex virus (HSV) transmission. Although rare, it can lead to severe disease and neonatal death. Between 1981 and 2011, neonatal herpes incidence has been monitored every five years in the Netherlands showing an increase over time. We investigated the further course of neonatal herpes incidence between 2012 and 2015, and studied longitudinal trends between 1999 and 2015. Additionally, we explored guideline adherence by health care professionals as this may contribute to changes in neonatal herpes incidence.

Methods Questionnaires were sent to all paediatric (n=93), gynaecology (n=93) and microbiology (n=47) departments of all hospitals in the Netherlands, inquiring about the number of neonatal herpes cases and guideline adherence between 2012 and 2015. Guideline adherence from 2006–2011 was obtained from previous studies.

Incidence of neonatal HSV infections was calculated by combining data from paediatric and microbiology departments taking non-response rates into account. For trend analyses, the annual numbers of neonatal herpes cases from 1999 onwards were obtained from previous surveys and from The Netherlands Perinatal Registry (Perined). Incidence trend lines were smoothed by calculating Poisson regression splines.

Results During 2012–2015, neonatal herpes incidence was 4.8 per 1 00 000 newborns based on survey data and 3.4 per 1 00 000 newborns based on Perined data. Longitudinal trend analyses displayed a minor increasing trend between 1999 and 2015. Adherence of gynaecologists and paediatricians to Dutch guidelines in case of a primary maternal HSV infection was somewhat lower in 2012–2015 compared to 2006–2011 in terms of antiviral therapy provision and performance of an elective Caesarean section.

Conclusion Longitudinal analyses showed a minor increasing trend in neonatal herpes incidence. Underlying factors of this increase might be related to a lower guideline adherence by health care professionals or other factors such as an increased age of first HSV-1 infection. Efforts should be made to underline the importance of guideline adherence among gynaecologists and paediatricians.