Large for Gestational Age fetus in singleton, non-diabetic pregnancies, investigation and management (1242)

1. 18+0 - 21+6 weeks

At this gestation, AC/EFW is unlikely to be related to maternal glycaemic status 

Recommendation: 

If the AC/EFW is >97^th centile at the routine anomaly scan, an oral glucose tolerance test (OGTT) is NOT indicated unless there are any other risk factors for GDM. A follow up antenatal clinic appointment with repeat ultrasound scan for biometry should be scheduled at 36 weeks. 

2. 22+0 – 34+6 weeks 

Recommendations: 

If the symphysial-fundal height (SFH) is >97^th centile on routine measurement an ultrasound scan for fetal biometry should be arranged within the next 5 working days. SFH can be measured from 24 weeks but usually commences at the 28 week appointment.

• If the symphysial-fundal height (SFH) is >97^thcentile on routine measurement an ultrasound scan for fetal biometry should be arranged within the next 5 working days 
• If EFW ≤ 97^th centile, return to original care pathway. If the SFH remains above the 97^th centile on subsequent SFH measurements a repeat scan is not indicated unless there is a significant upward trend in the percentiles. 
• If EFW >97^th centile an OGTT should be arranged as soon as possible 
• If an OGTT has already been performed at an earlier gestation with a negative result, a repeat test should be undertaken if the following develop 
  • Glycosuria- 2+ or above on one occasion, 1+ on 2 or more occasions or polyhydramnios 
• An antenatal clinic appointment should be arranged to plan follow-up scans and discuss birth.  

3. After 35+0 weeks 

Recommendations: 

• If the SFH is >97^thcentile, an ultrasound scan for fetal biometry should be arranged within the next 5 working days 
• If EFW ≤97^th centile, return to original care pathway 
• If EFW >97^th centile:  
• An OGTT is not recommended at  ≥35+0  
• HbA1C and random blood glucose should be taken and antenatal clinic appointment arranged to discuss birth options. 
• If the scan was done at <36+0 weeks consider repeat scan prior to birth planning.  

The uncertainty of benefits and risks of induction of labour versus expectant management should be discussed with a woman and documented in Badgernet. Following this discussion, induction of labour can be offered from 38+0 weeks. 

• Women may wish to request a caesarean birth after discussion of the risks and benefits.  Planned caesarean birth is recommended from 39+0 weeks onwards unless there are other indications. It should always be discussed for EFW of over 5kg. 

• Documentation of any discussions and completion of the PPH risk assessment checklist should be completed on Badgernet. 

A significant limitation of the Big Baby Trial was the poor predictive value of scan estimated fetal weight. At birth, only 40% (4 in 10) of babies identified as LGA on scan had a birthweight >90% centile. So, 6 in 10 babies identified as LGA were not LGA.  

Main findings 

There was a non-significant reduction in shoulder dystocia in the induction of labour group versus the standard care group in the intention to treat analysis, however in the per protocol analysis there was a reduction in shoulder dystocia with IOL between 38+0 and 38+4 weeks. This was felt to be due to the higher proportion of earlier than expected births in the standard care group (25%, 1 in 4, of pregnancies in the standard care group were delivered early) reducing the intended between group differences in gestational age and birth.

As the incidence of harm secondary to shoulder dystocia is small, three composite harm outcomes were prespecified; 

Intrapartum birth injury (fractures, brachial plexus injury or both) 

There were no significant differences between the induction of labour group versus expectant management group. 

Maternal intrapartum complications (3^rd/4^th degree perineal tears, cervical injury or primary PPH) 

Women in the induction group had fewer primary post-partum haemorrhages and there were no significant differences in the incidence of third and 4^th degree tears between the two groups. This is in contrast to the findings of the NICE evidence review (Nov 2021) which found an increase in 3^rd and 4^th degree tears in the induction of labour group.

Prematurity associated problems (use of phototherapy, respiratory support or both) 

There were no significant differences in prematurity associated problems between the two groups. 

The authors also concluded that although associated with an extra half day in hospital pre-birth, induction of labour can lead to a reduction in operative birth. 

Discussion aid