BMJ (e), 367:5517, 1-13. BMJ Publishing Group BMJ. British Medical Journal (Online), 367 BMJ-British medical journal, 367:l5517. BMJ Publishing Group BMJ-British Medical Journal, 367:5517. BMJ PUBLISHING GROUP Henrichs, J, Verfaille, V, Jellema, P, Viester, L, Pajkrt, E, Wilschut, J, Van Der Horst, H E, Franx, A & De Jonge, A 2019, ' Effectiveness of routine third trimester ultrasonography to reduce adverse perinatal outcomes in low risk pregnancy (the IRIS study) : nationwide, pragmatic, multicentre, stepped wedge cluster randomised trial ', The BMJ, vol. 367, l5517 . https://doi.org/10.1136/bmj.l5517 BMJ (Clinical research ed.), 367:l5517. British Medical Association British Medical Journal, 367. BMJ PUBLISHING GROUP The BMJ, 367:l5517. BMJ Publishing Group The BMJ