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Associations between consumption of coffee and caffeinated soft drinks and late stillbirth—Findings from the Midland and North of England stillbirth case-control study

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Abstract

Objective

The consumption of caffeinated drinks and soft drinks is widespread in society, including by pregnant women. Data regarding the association of caffeine intake and stillbirth are varied. We aimed to investigate the degree of consumption of caffeinated drinks or soft drinks in the last four weeks of pregnancy in women who experienced a late stillbirth compared to women with ongoing live pregnancies at similar gestation. Influences on maternal caffeine intake and soft drink consumption during pregnancy were also investigated.

Study Design

A case-control study undertaken in 41 maternity units in the United Kingdom. Cases were women who had a singleton non-anomalous stillbirth ≥28 weeks’ gestation (n = 290) and controls were women with an ongoing pregnancy at the time of interview (n = 729). Data were collected using an interviewer-administered questionnaire which included questions regarding consumption of a variety of caffeinated drinks and soft drinks in the last four weeks of pregnancy as well as other behaviours (e.g. cigarette smoking).

Results

Multivariable analysis adjusting for co-existing demographic and behavioural factors found the consumption of instant coffee, energy drinks and cola were associated with increased risk of stillbirth. There was an independent association between caffeine intake and late stillbirth (adjusted Odds Ratio 1.27, 95 % Confidence Interval (95 %CI) 1.14, 1.43 for each 100 mg increment/day). 15 % of cases and 8% of controls consumed more than the World Health Organisation (WHO) recommendation (>300 mg of caffeine/day; aOR 2.30, 95 % CI 1.40, 4.24). The population attributable risk for stillbirth associated with >300 mg of caffeine/day was 7.4 %. The majority of respondents reduced caffeine consumption in pregnancy. Midwives and internet resources were the most frequently used sources of information which influenced maternal behaviour with regard to soft drinks and caffeine, and this did not differ between cases and controls.

Conclusions

Women should be informed that consumption of caffeine during pregnancy is associated with increased risk of stillbirth, particularly at levels greater than recommended by the WHO (>300 mg/day). Recommendations from midwives and internet-based resources are likely to be the most effective means to influence maternal behaviour.

Introduction

Stillbirth is an important public health problem with enduring impact not only in terms of lives lost but also with economic, psychological and social impacts upon affected families. [1,2] One approach to reducing stillbirth is to identify factors associated with increased risk so that their effects may be reduced. Epidemiological studies have identified risk factors for stillbirth, some of which are modifiable (e.g. cigarette smoking, drug misuse) and others which are not (e.g. maternal age, ethnicity) [3].

The Stillbirth Priority Setting Partnership identified a research need to ascertain modifiable risk factors for late stillbirth [4]. The Midland and North of England Stillbirth Study (MiNESS) was a case control study which aimed to identify modifiable risk factors for late stillbirth (≥28 weeks’ gestation) [5]. Due to their ubiquitous consumption, 80 % of the UK population drinks instant coffee and on average 211.5 L of soft drinks (many of which contain high levels of caffeine) were consumed per capita per year [6]. Accordingly, this study included questions about intake of caffeinated drinks and soft drinks during pregnancy. To date, the evidence linking caffeine intake and stillbirth shows variable effect size and some studies focus on coffee consumption rather than consumption of any source of caffeine [[7], [8], [9]]. Presently, the World Health Organisation recommends that high caffeine intake (>300 mg/day) is decreased to reduce the risk of pregnancy loss and the UK National Health Service recommends caffeine intake is <200 mg/day during pregnancy [10]. Given that caffeinated drinks, are widely consumed we aimed to investigate whether there is a relationship between consumption of these beverages and the risk of late stillbirth.

Section snippets

Methods

MiNESS was a prospective case-control study undertaken in 41 secondary and tertiary maternity units in the UK [5]. The methodology has been described in detail previously and was conducted in accordance with the published protocol [5,11]. Following ethical approval (Ref 13/NW/0174) and study registration (NCT02025530) participants were recruited between April 2014 and March 2016. Cases were singleton stillbirths occurring ≥28 weeks’ gestation with no evidence of congenital anomaly. Women who

Results

During the recruitment period, 3490 women were identified as potentially eligible participants for MiNESS (660 cases and 2830 controls, Fig. 1), 760 women could not be contacted (77 cases (11 %), and 683 controls (24 %)) and 1700 women did not consent to participate (287 cases (43 %) and 1413 controls (50 %)). Six participants were excluded after data collection as five stillbirths had previously unidentified congenital abnormalities detected on post-mortem and one control participant had a

Discussion

This study found an association between caffeine intake and late stillbirth; this appears to be mediated through an increased intake of instant coffee, cola and energy drinks in cases compared to controls. Tea consumption, the most widely consumed caffeinated drink (1.44 servings/day in controls) did not differ between cases and controls. Although the majority of participants (54.5 %) reduced their caffeine intake during pregnancy, a small proportion (3%) increased it and over 15 % of cases and

Funding

The Midland and North of England Stillbirth Study was funded by grant GN2156 from Action Medical Research, Cure Kids and Sands. AH receives salary support from Tommy’s. EM and JT were supported by Cure Kids.

Declaration of Competing Interest

All authors declare that they have no competing interests.

Contribution to authorship

AH, TS, BM, DR, EM & LM contributed to all aspects of the study design and obtained funding. AH had overall responsibility for the study. JB coordinated the running of the study. KT and LR analysed the data with input from AH. All authors were responsible for the drafting of the manuscript. All authors gave approval for the final version of the manuscript.

Details of ethical approval

This study was reviewed by NRES Committee North West - Greater Manchester Central Reference (13/NW/0874) on 24th January 2014.

Data sharing statement

No additional data from the MiNESS study are available from a repository. Anonymised data is available on request to the corresponding author.

Acknowledgements

The authors thank all the participants who participated in interviews in order to help us better understand stillbirth. The authors would also like to thank the Principal Investigators, Research Midwives and Nurses at the following institutions for their hard work and dedication to this study: Airedale NHS Foundation Trust, Birmingham Women’s NHS Trust, Blackpool Teaching Hospitals NHS Foundation Trust, Bradford Teaching Hospitals NHS Foundation Trust, Buckinghamshire Healthcare NHS Trust,

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