Effect of first trimester crown rump length measurement on rates of induction of labour for postdates.

INTERVENTION:

The control group will continue with routine antenatal care with ultrasound performed for the usual indications. The intervention group will have an ultrasound scan between 8 and 12 weeks gestation to measure the crown‐rump length (CRL) and if there is a discrepancy of greater than 5 days between the estimated date of delivery (EDD) calculated form the last menstrual period and that by CRL the EDD will be revised to that derived by scan. The EDD will be entered in the patient's obstetric notes and all subsequent management decisions will be based on this assessment of gestational age.

CONDITION:

Pregnancy and childbirth: Childbirth ; Pregnancy and Childbirth ; Childbirth

PRIMARY OUTCOME:

Rates of induction of labour for postdates

SECONDARY OUTCOME:

1. The characteristics of labour with respect to the length of labour, the mode of delivery, the immediate perinatal outcome, analgesic requirements for labour and the overall client satisfaction with labour; 2. Rates of gestation dependent events in pregnancy ‐ false positive and negative outcomes from maternal serum screening; 3. The management of early pregnancy complications

INCLUSION CRITERIA:

Women in the first trimester of pregnancy who do not require a first trimester ultrasound for any other clinical indication.