We would like to thank Drs Dickson and Zaklama for the important issues raised. To obtain a sample of lactate, one incision is sufficient, unlike more than one incision needed at times with pH measurements. This is because the lactate meter needs only 5 μl of blood for analysis and has in clinical practice reduced scalp blood sampling failure rate to almost nil2. In the present study, we were able to get blood at repetitive samples by only weeping the previous incision in most cases because the volume of sample needed was small.
The sampling was carried out in the second stage (i.e. all women were fully dilated) and therefore, it was very easy to get access with an amnioscope. The procedure was done without any alteration of the women's position. (The standard maternal position during the second stage is lying on her back.) The sampling time did not last for more than 1 minute because only a small sampling volume (5 μl) is needed and it produced minimal discomfort. If major discomfort was mentioned, the sampling was abandoned.
The study was explained to the women at the beginning of labour and they consented. This was followed by talking to them again in the second stage. The recruitment was done by local midwives after they explained the procedure to the women. The Swedish author was working in Singapore and did not go to Asia especially for the study. The Japanese author provided advice regarding the use of the equipment. The hospital was selected because of the large number of deliveries (18,000) per annum, and thus, to collect a reasonable number of cases within a limited period of time.
There is emerging evidence that lactate may be a more reliable indicator of long term neurological outcome of the newborn. Interventions based on metabolic acidosis based on lactate should reduce operative delivery for presumed fetal distress. To use this measurement, normal ranges in the second stage need to be established, as there may be a component from the mother with increased duration of pushing. We thank the mothers and babies who participated in the study and believe that the results of the study will help to reduce operative deliveries without compromising the newborn.