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Induction of labour at 41 weeks versus expectant management and induction of labour at 42 weeks (SWEdish Post-term Induction Study, SWEPIS): multicentre, open label, randomised, superiority trial

BMJ 2019; 367 doi: https://doi.org/10.1136/bmj.l6131 (Published 20 November 2019) Cite this as: BMJ 2019;367:l6131

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When to induce late term pregnancies

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Re: Induction of labour at 41 weeks versus expectant management and induction of labour at 42 weeks (SWEdish Post-term Induction Study, SWEPIS): multicentre, open label, randomised, superiority trial

Dear Editor,

Dr Pelle Lindqvist and Dr Sofie Graner forward comments and critique on the SWEPIS trial recently published in the BMJ1 and they propose that instead of induction of labour (IOL) at 41 weeks of gestation ”a more evidence based alternative could be to perform a late routine US scan with the aim to identify small for gestational age (SGA) pregnancies or other signs of growth restriction”. However, no RCTs investigating and supporting such a regime have been published.

We apologize for that the protocol published in Elden et al. 2 (submitted in April 2015) was a preliminary version and the final protocol was set in early 2016 (March 11, 2016) well before start of the SWEPIS trial in May 2016. It is clearly stated in the BMJ publication1 that ”outside the Stockholm region, 41 week scans were not routinely performed”. Therefore, the stillbirths were certainly not the result of ”protocol violations”.

We are aware of that growth restricted fetuses are at increased risk of perinatal death but it is also clear from Divon et al.3 that only a minority (about 20 %) of stillbirths at late term and post term pregnancies are SGA, (in SWEPIS only one of six cases of perinatal death was SGA). Therefore, it is unlikely that a 41 week US scan would prevent most of the perinatal deaths occurring after 41 weeks. Further, we have no information on if these women with perinatal deaths in SWEPIS in fact went through a clinically indicated US scan in gestational week 41+ even though they did not belong to the Stockholm area where scans were performed routinely. Another observation is that the perinatal adverse outcome (including perinatal death) was not significantly lower in the group with routine scan at 41 weeks compared with indicated scans (routine in most Swedish centers) in the retrospective cohort study (not randomized) referred to by Drs Lindqvist/Graner4. Unfortunately, we still lack a fetal monitoring technique that effectively predicts and prevents stillbirths in late term/post term pregnancies. The SWEPIS and INDEX5 trials indicate that IOL at 41 weeks of gestation reduces perinatal adverse outcomes without negatively affecting maternal outcomes or increases in cesarean or instrumental deliveries.

1. Wennerholm UB, Saltvedt S, Wessberg A, Alkmark M, Bergh C, Wendel SB, Fadl H, Jonsson M, Ladfors L, Sengpiel V, Wesström J, Wennergren G, Wikström AK, Elden H,Stephansson O, Hagberg H. Induction of labour at 41 weeks versus expectant management and induction of labour at 42 weeks (SWEdish Post-term Induction Study, SWEPIS): multicentre, open label, randomised, superiority trial. BMJ. 2019 Nov 20;367:l6131
2. Elden H, Hagberg H, Wessberg A, Sengpiel V, Herbst A, Bullarbo M, et al. Study protocol of SWEPIS a Swedish multicentre register based randomised controlled trial to compare induction of labour at 41 completed gestational weeks versus expectant management and induction at 42 completed gestational weeks. BMC Pregnancy Childbirth 2016;16:49.
3. Divon MY, Haglund B, Nisell H, Otterblad PO, Westgren M. Fetal and neonatal mortality in the postterm pregnancy: the impact of gestational age and fetal growth restriction. Am J Obstet Gynecol 1998;178(4):726-31.
4. Lindqvist PG, Pettersson K, Moren A, Kublickas M, Nordstrom L. Routine ultrasound examination at 41 weeks of gestation and risk of post-term severe adverse fetal outcome: a retrospective evaluation of two units, within the same hospital, with different guidelines. BJOG 2014;121(9):1108-15.
5. Keulen JK, Bruinsma A, Kortekaas JC, van Dillen J, Bossuyt PM, Oudijk MA, Duijnhoven RG, van Kaam AH, Vandenbussche FP, van der Post JA, Mol BW, de Miranda E. Induction of labour at 41 weeks versus expectant management until 42 weeks (INDEX): multicentre, randomised non-inferiority trial. BMJ. 2019 Feb 20;364:l344.

Competing interests: No competing interests

02 December 2019
Ulla-Britt Wennerholm
Senior consultant and associate professor in obstetrics and gynecology
Christina Bergh senior consultant and professor in obstetrics and gynecology, Henrik Hagberg, senior consultant and professor in obstetrics and gynecology., on behalf of the SWEPIS trial group
Deaprtment of Obstetrics and Gynecology, Sahlgrenska University Hospital, Göteborg, Sweden
Department of Obstetrics and Gynecology, Sahlgrenska University Hospital, 416 85 Göteborg Sweden