Full length article| Volume 220, P25-29, January 2018

Exploring the newborn head diameters in relation to current obstetric forceps’ dimensions: A systematic review

Published:October 28, 2017DOI:



      The aim of this study was to systematically search the literature for studies that reported term neonate head size and shape, in an attempt to determine the most appropriate dimensions for the obstetric forceps.

      Study design

      We searched the Ovid Medline, Ovid Embase and Ebscohost CINAHL databases from inception to February 2016. We predefined inclusion criteria to identify studies in which head width and length of asymptomatic, term neonates were measured soon after birth using direct, non-photographic methods A bespoke quality assessment score was used to evaluate the identified studies.


      Seven studies were identified which measured head width (biparietal diameter) in 551 neonates; giving a mean value of 94.0 mm (range 90.7 mm–95.5 mm). We identified one study which measured head length (mentovertical diameter) in 38 neonates; which gave a mean value of 134.5 mm (range 129 mm–139 mm).


      This data, in conjunction with measurements of Neville Barnes’ and Wrigley’s forceps from our previous study, indicates current obstetric forceps’ blades are too long, and close together. Potentially, this could be contributing to neonatal and maternal injuries associated with operational vaginal deliveries.


      To read this article in full you will need to make a payment

      Purchase one-time access:

      Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online access
      One-time access price info
      • For academic or personal research use, select 'Academic and Personal'
      • For corporate R&D use, select 'Corporate R&D Professionals'


        • HSCIC
        NHS maternity statistics – England, 2014–15.
        • DiMatteo M.R.
        • et al.
        Cesarean childbirth and psychosocial outcomes: a meta-analysis.
        Health Psychol. 1996; 15: 303-314
        • Murphy D.J.
        • et al.
        Early maternal and neonatal morbidity associated with operative delivery in second stage of labour: a cohort study.
        Lancet. 2001; 358: 1203-1207
        • Liebling R.E.
        • et al.
        Pelvic floor morbidity up to one year after difficult instrumental delivery and cesarean section in the second stage of labor: a cohort study.
        Am J Obstet Gynecol. 2004; 191: 4-10
        • Bahl R.
        • Strachan B.
        • Murphy D.J.
        Outcome of subsequent pregnancy three years after previous operative delivery in the second stage of labour: cohort study.
        BMJ. 2004; 328: 311
        • Patel R.R.
        • Murphy D.J.
        Forceps delivery in modern obstetric practice.
        BMJ. 2004; 328: 1302-1305
        • Wray J.
        Review of the national sentinel caesarean section audit report.
        Pract Midwife. 2001; 4: 24-25
        • Johanson R.B.
        • Menon B.K.
        Vacuum extraction versus forceps for assisted vaginal delivery.
        Cochrane Database Syst Rev. 2000; 2: CD000224
        • Kabiru W.N.
        • et al.
        Trends in operative vaginal delivery rates and associated maternal complication rates in an inner-city hospital.
        Am J Obstet Gynecol. 2001; 184: 1112-1114
        • O'Mahony F.
        • Hofmeyr G.J.
        • Menon V.
        Choice of instruments for assisted vaginal delivery.
        Cochrane Database Syst Rev. 2010; 11: CD005455
        • Caughey A.B.
        • et al.
        Forceps compared with vacuum: rates of neonatal and maternal morbidity.
        Obstet Gynecol. 2005; 106: 908-912
        • Keriakos R.
        • Sugumar S.
        • Hilal N.
        Instrumental vaginal delivery–back to basics.
        J Obstet Gynaecol. 2013; 33: 781-786
        • Demissie K.
        • et al.
        Operative vaginal delivery and neonatal and infant adverse outcomes: population based retrospective analysis.
        BMJ. 2004; 329: 24-29
        • Hirshberg A.
        • Srinivas S.K.
        Role of operative vaginal deliveries in prevention of cesarean deliveries.
        Clin Obstet Gynecol. 2015; 58: 256-262
        • Okunwobi-Smith Y.
        • Cooke I.
        • MacKenzie I.Z.
        Decision to delivery intervals for assisted vaginal vertex delivery.
        BJOG. 2000; 107: 467-471
        • Zwecker P.
        • Azoulay L.
        • Abenhaim H.A.
        Effect of fear of litigation on obstetric care: a nationwide analysis on obstetric practice.
        Am J Perinatol. 2011; 28: 277-284
        • Ismail A.Q.
        • Ismail K.M.
        Exploring variation in dimensions of obstetric forceps.
        Eur J Obstet Gynecol Reprod Biol. 2016; 198: 170-171
        • Kurmanavicius J.
        • et al.
        Fetal ultrasound biometry: 1. Head reference values.
        Br J Obstet Gynaecol. 1999; 106: 126-135
        • Chitty L.S.
        • et al.
        Charts of fetal size: 2. Head measurements.
        Br J Obstet Gynaecol. 1994; 101: 35-43
        • Souza S.W.
        • Ross J.
        • Milner R.D.
        Alterations in head shape of newborn infants after caesarean section or vaginal delivery.
        Arch Dis Child. 1976; 51: 624-627
        • Dangerfield P.H.
        • Taylor C.J.
        Anthropometric standards for term neonates.
        Early Hum Dev. 1983; 8: 225-233
        • Jordaan H.V.
        Comparative cranial morphology in the newborn.
        S Afr Med J. 1962; 36: 690-705
        • Sinha P.
        • Tamang B.K.
        • Chakraborty S.
        Craniofacial anthropometry in newborns of Sikkimese origin.
        J Laryngol Otol. 2014; 128: 527-530
        • Largo R.H.
        • Duc G.
        Head growth and changes in head configuration in healthy preterm and term infants during the first sex months of life.
        Helv Paediatr Acta. 1978; 32: 431-442
        • Todros T.
        • et al.
        Head shape and size and body weight in the newborn infant.
        Eur J Obstet Gynecol Reprod Biol. 1985; 19: 1-5
        • Kriewall T.J.
        • Stys S.J.
        • McPherson G.K.
        Neonatal head shape after delivery: an index of molding.
        J Perinat Med. 1977; 5: 260-267
        • Sorbe B.
        • Dahlgren S.
        Some important factors in the molding of the fetal head during vaginal delivery–a photographic study.
        Int J Gynaecol Obstet. 1983; 21: 205-212
        • Baskett T.F.
        • C.A
        • Arulkumaran S.
        Munro Kerr's operative obstetrics.
        12th ed. Saunders, Elsevier, 2014
        • Collier J.
        • L.M
        • Amarakone K.
        Oxford handbook of clinical specialties.
        9th ed. Oxford University Press, 2013
        • de Kock J.
        • v.d.W.C
        Maternal and newborn care: a complete guide for midwives and other health professionals.
        Juta Academic, 2004
        • Di Renzo G.C.
        • M.A
        Cesarean delivery: a comprehensive illustrated practical guide.
        CRC Press, Taylor & Francis Group, 2016
        • Hacker N.F.
        • G.J
        • Hobel C.J.
        Hacker & Moore's essentials of obstetrics and gynecology.
        6th ed. Elsevier, 2015
        • Kenny L.C.
        • MJ
        Obstetrics by ten teachers.
        12th ed. 2017
      1. KP, H., Obstetrics Illustrated. 3rd ed. Churchill Livingstone, Elsevier 2009.

        • MB
        Emergencies around childbirth a handbook for midwives.
        3rd. ed. CRC Press, Taylor & Francis Group, 2016
        • Magowan B.A.
        • O.P
        • Thomson A.
        Clinical obstetrics and gynaecology.
        3rd. ed. 2014
        • Marshall J.E.
        • R.M
        Myles' textbook for midwives.
        16th ed. Churchill Livingstone, Elsevier, 2014
        • Oats J.
        • Abraham S.
        Llewellyn-Jones fundamentals of obstetrics and gynaecology.
        10th ed. Elsevier, 2016
        • Warren R.
        • Abraham S.
        Best practice in labour and delivery.
        Cambridge University Press, 2009
        • Van Pelt J.K.
        Measurements of the diameters of the Fœtal head at term: collected from seven hundred cases of labour.
        Am J Med Sci. 1860; 39: 111-114
        • Chandraharan E.
        • Arulkumaran S.
        Obstetric and intrapartum emergencies: a practical guide to management.
        Cambridge University Press, 2013
        • Luesley D.
        • Kilby M.
        Obstetrics & gynaecology: an evidence-based text for MRCOG.
        3rd ed. 2016