Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2018 Dec 3;147:1-7.
doi: 10.1017/S0950268818003254. Online ahead of print.

The Association Between Seasonal Influenza-Like Illness Cases and Foetal Death: A Time Series Analysis

Affiliations
Free PMC article

The Association Between Seasonal Influenza-Like Illness Cases and Foetal Death: A Time Series Analysis

I S Rasmussen et al. Epidemiol Infect. .
Free PMC article

Abstract

It has been reported that foetal death follows a seasonal pattern. Influenza virus infection has been postulated as one possible contributor to this seasonal variation. This ecological study explored the temporal association between the influenza activity and the frequency of foetal death. Time series analysis was conducted using weekly influenza-like illness consultation proportions from the Danish sentinel surveillance system and weekly proportions of spontaneous abortions and stillbirths from hospital registers from 1994 to 2009. The association was examined in an autoregressive (AR) integrated (I) moving average (MA) model and subsequently analysed with cross-correlation functions. Our findings confirmed the well-known seasonality in influenza, but also seasonality in spontaneous abortion. No clear pattern of seasonality was found for stillbirths, although the analysis exposed dependency between observations. One final AR integrated MA model was identified for the influenza-like illness (ILI) series. We found no statistically significant relationship between weekly influenza-like illness consultation proportions and weekly spontaneous abortion proportions (five lags: P = 0.52; 11 lags: P = 0.91) or weekly stillbirths (five lags: P = 0.93; 11 lags: P = 0.40). Exposure to circulating influenza during pregnancy was not associated with rates of spontaneous abortions or stillbirths. Seasonal variations in spontaneous abortion were confirmed and this phenomenon needs further investigation.

Keywords: Foetal death; influenza (seasonal); maternal infection; seasonality.

Conflict of interest statement

None.

Figures

Fig. 1.
Fig. 1.
Four-week MA of weekly proportions of: influenza-like illness patients reported by general practitioners, spontaneous abortions and stillbirths occurring over the period of 1994–2009.
Fig. 2.
Fig. 2.
Behaviour, ACF, PACF and IACF of the non-stationary and stationary influenza series. The four lower plots represent the stationarised influenza series’ (influenza(1)) behaviour, ACF, PACF and IACF.
Fig. 3.
Fig. 3.
CCF plot of the pre-whitened influenza series and the spontaneous abortion series, Denmark, 1994–2009.
Fig. 4.
Fig. 4.
CCF plot of the pre-whitened influenza series and the stillbirth series, Denmark, 1994–2009.

Similar articles

See all similar articles

Cited by 1 article

References

    1. Wilcox AJ (2010) Fertility and Pregnancy: An Epidemiologic Perspective. Oxford, New York: Oxford University Press.
    1. Man J et al. (2016) Stillbirth and intrauterine fetal death: factors affecting determination of cause of death at autopsy: cause of intrauterine death. Ultrasound in Obstetrics & Gynecology 48, 566–573. - PubMed
    1. Hoyert DL and Gregory ECW (2016) Cause of fetal death: data from the fetal death report, 2014. National Vital Statistics Reports 65, pp. 1–25. Published online: 2016. - PubMed
    1. Czeizel A, Bognár Z and Rockenbauer M (1984) Some epidemiological data on spontaneous abortion in Hungary, 1971–80. Journal of Epidemiology and Community Health 38, 143–148. - PMC - PubMed
    1. Strand LB, Barnett AG and Tong S (2011) The influence of season and ambient temperature on birth outcomes: a review of the epidemiological literature. Environmental Research 111, 451–462. - PubMed
Feedback