We set out to look for evidence from randomised controlled trials on the effectiveness and safety of stimulating the baby's scalp as a second-line test of well-being when there are concerns about the baby's heart rate monitoring.
What is the issue?
Women with complicated pregnancies are recommended continuous monitoring of the baby's heart rate using an electronic recorder called a CTG. Babies commonly demonstrate abnormal features on the CTG during labour. In some cases the abnormal features are of sufficient concern to warrant an emergency caesarean section. To reduce the chance of an unnecessary caesarean section additional 'second-line' tests can be offered. One such test is where the baby's scalp is stimulated vaginally in an attempt to cause an increase in the baby's heart rate. This healthy response suggests that the baby is receiving enough oxygen. An alternative approach is to take a small blood sample from the baby's scalp and test the acid-base level in the blood.
Why is this important?
If stimulation of the baby's scalp as a second-line test of well-being is demonstrated to be safe and effective, then it may be possible to reduce the chance of an unnecessary caesarean section for women in labour.
What evidence did we find?
We searched for evidence on 18 October 2022 and identified two eligible studies (involving 377 women). A pilot study of 50 women in Ireland compared digital fetal scalp stimulation (dFSS) and CTG with fetal blood sampling (FBS) and CTG. A study in India of 327 women compared manual fetal scalp stimulation (FSS) (abdominal side to side movement of the fetal head or vaginal pinching of the fetal scalp) and CTG with CTG alone. In both studies, women and hospital staff were aware that fetal scalp stimulation had been performed. This may have had an impact on the results. Both studies were conducted in hospitals and recruited women in labour at term with a single baby presenting head first. Overall, the included studies were at moderate or unclear risk of bias, and the certainty of the generated evidence was very low or unclear.
dFSS and CTG versus FBS and CTG
There were no perinatal deaths and no data reported on disability in the babies at or after 12 months. We found very low-certainty evidence that stimulation of the baby's scalp in addition to CTG may lower the risk of caesarean section compared to scalp blood sampling and CTG (1 pilot trial; 50 women). There were no babies born with evidence of brain injury during labour. There was no difference in the risk of assisted vaginal birth by vacuum or forceps, or in the rate of spontaneous vaginal birth. The acceptability of the procedures to the mother was not reported.
FSS and CTG versus CTG alone
There were no perinatal deaths and no data reported on disability in the babies at or after 12 months. We found that stimulation of the baby's scalp in addition to CTG had little or no difference in the risk of caesarean section compared to CTG alone (1 trial; 327 women). There were no babies born with evidence of brain injury during labour. There was no difference in the risk of assisted vaginal birth by vacuum or forceps, or in the rate of spontaneous vaginal birth. All of the evidence was found to be of very low certainty. The acceptability of the procedures to the mother was not reported.
What does this mean?
The evidence is unclear whether stimulating a baby's scalp in labour is a safe and effective way to confirm the baby's well-being in labour. Further high-quality studies of adequate sample size, including a broad range of settings and eligibility criteria, are required to evaluate this research question.
There is very low-certainty evidence available which makes it unclear whether stimulating the fetal scalp is a safe and effective way to confirm fetal well-being in labour. Evidence was downgraded based on limitations in study design and imprecision. Further high-quality studies of adequate sample size are required to evaluate this research question. In order to be generalisable, these trials should be conducted in different settings, including broad clinical criteria at both preterm and term gestational ages, and standardising the method of stimulation. There is an ongoing study (FIRSST) that will be incorporated into this review in a subsequent update.
Continuous fetal heart rate monitoring by cardiotocography (CTG) is used in labour for women with complicated pregnancies. Fetal heart rate abnormalities are common and may result in the decision to expedite delivery by caesarean section. Fetal scalp stimulation (FSS) is a second-line test of fetal well-being that may provide reassurance that the labour can continue.
To evaluate methods of FSS as second-line tests of intrapartum fetal well-being in cases of non-reassuring CTG. FSS and CTG were compared to CTG alone, and to CTG with fetal blood sampling (FBS).
We searched Cochrane Pregnancy and Childbirth’s Trials Register (which includes trials from CENTRAL, MEDLINE, Embase, CINAHL, the WHO ICTRP and conference proceedings), ClinicalTrials.gov (18 October 2022), and reference lists of retrieved studies.
Eligible studies were randomised controlled trials (RCTs) that compared any form of FSS to assess fetal well-being in labour. Quasi-RCTs, cluster-RCTs and studies published in abstract form were also eligible for inclusion, but none were identified.
Two review authors independently assessed studies for inclusion and risk of bias, extracted data and checked them for accuracy. We assessed the certainty of the evidence using the GRADE approach.
Two trials, involving 377 women, met the inclusion criteria for this review. Both trials were conducted in hospital settings and included women with singleton, term (37+0 weeks or more) pregnancies, a cephalic presentation, and abnormal CTG. Follow-up was until hospital discharge after the birth. A pilot trial of 50 women in a high-income country (Ireland) compared CTG and digital fetal scalp stimulation (dFSS) with CTG and fetal blood sampling (FBS). A single-centre trial of 327 women in a lower middle-income country (India) compared CTG and manual fetal stimulation (abdominal or vaginal scalp stimulation) with CTG alone. The two included studies were at moderate or unclear risk of bias. Both trials provided clear information on allocation concealment but it was not possible to blind participants or health professionals in relation to the intervention. Although objective outcome measures were reported, outcome assessment was not blinded or blinding was unclear.
dFSS and CTG versus FBS and CTG
There were no perinatal deaths and data were not reported for neurodevelopmental disability at >/= 12 months. The risk of caesarean section (CS) may be lower with dFSS compared to FBS (risk ratio (RR) 0.38, 95% confidence interval (CI) 0.16 to 0.92; 1 pilot trial, 50 women; very low-certainty evidence) but the evidence is very uncertain. There were no cases of neonatal encephalopathy reported. The evidence was also very uncertain between dFSS and FBS for assisted vaginal birth (RR 1.44, 95% CI 0.76 to 2.75; very low-certainty evidence) and for the spontaneous vaginal birth rate (RR 2.33, 95% CI 0.68 to 8.01, very low-certainty evidence). Maternal acceptability of the procedures was not reported.
FSS and CTG versus CTG alone
Manual stimulation of the fetus was performed either abdominally (92/164) or vaginally (72/164). There were no perinatal deaths and data were not reported for neurodevelopmental disability at >/= 12 months. There may be little differences in the risk of CS on comparing manual fetal stimulation and CTG with CTG alone (RR 0.83, 95% CI 0.59 to 1.18; 1 trial, 327 women; very low-certainty evidence), but again the evidence was very uncertain. There were no cases of neonatal encephalopathy reported. There may be no differences in the risk of assisted vaginal birth (RR 1.43, 95% CI 0.78 to 2.60; very low-certainty evidence) or in the rates of spontaneous vaginal birth (RR 1.01, 95% CI 0.85 to 1.21, very low-certainty evidence), but again the evidence is very uncertain. Maternal acceptability of abdominal stimulation/FSS was not reported although 13 women withdrew consent after randomisation due to concerns about fetal well-being.