[CG] Late booking in pregnancy: management of women who book after 25+0 weeks gestation


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The aim of this guideline is to provide information on the management of women with an unknown estimated delivery date, or who book with maternity services after 25+0 weeks gestation.

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Introduction and Background

Accurate dating of pregnancy is crucial for determining gestational age. BMUS guidelines state that the most accurate measurement for dating a pregnancy is a crown rump length, taken between 7 and 13 weeks gestation.1 Pregnancies without ultrasonic examination before 25+1 weeks should be considered sub-optimally dated.

Booking late is known to be associated with poorer obstetric and neonatal outcomes. These women often have complex social issues.

No established guideline currently exists to advise on the antenatal management of these women. This guideline aims to standardise current antenatal practice.

First Visit/Point of contact

  • Women without an EDD should be seen through the consultant clinic and have hospital based care.
  • The reason for late booking should be explored and if there are any concerns regarding the woman’s mental health or any causes for concern for the welfare of the unborn baby then the necessary referrals should be made.
  • Booking bloods including for screening for BBV’s should be obtained urgently. This should be performed at first hospital contact which may be in Day Care/Maternity Assessment. This should not be deferred until the next antenatal clinic.
    • The results of communicable diseases can effect the management of pregnancy and delivery. See NHSGG Virology guidance
  • Inform patient that an accurate EDD cannot be offered. Explain that they are too late to be offered screening for Down syndrome.
  • Perform USS for fetal anomaly and fetal growth.
  • A clinical estimate of gestational age will be provided by the consultant obstetrician following the first scan and this will be used to guide management.

Subsequent Visits

  • Women should have serial growth scans every 4 weeks, followed by medical review.
  • Suspected fetal growth restriction, oligohydramnios or abnormal end diastolic flow on umbilical artery Doppler should be managed in keeping with local policy.
  • When AC measurement reaches 10th centile for 37 weeks gestation (>290mm), USS for assessment of growth, LV and Doppler should be offered every 2 weeks.
  • Offer induction of labour for usual obstetric reasons or if the pregnancy has reached 41 weeks by the best clinical estimate.2

Previous LUSCS

  • If patient is suitable and wishes VBAC – manage as per VBAC guideline.
  • If delivery by caesarean section is required, deliver at best estimate of 39-40 weeks gestation with steroid cover. This should be discussed with the woman’s consultant.
  1. Loughna P, Chitty L, Evans T, Chudleigh T. Fetal size and dating: charts recommended for clinical obstetric practice. Ultrasound 2009; 17(3): 161-167
  2. The American College of Obstetricans and Gynaecologists. Committee Opinion Number 688 – Management of suboptimally dated pregnancies. Vol. 129, No. 3, March 2017

Last reviewed: 26 April 2018

Next review: 01 April 2022

Author(s): H Richardson ST6 / F Mackenzie Consultant PRM

Approved By: Clinical Governance Group