|Aquabirths Research Review:
Title: “Maternal and perinatal outcomes amongst low risk women giving birth in water compared to six birth positions on land. A descriptive cross sectional study in a birth centre over 12 years”.
Authors: Hannah G. Dahlen, Helen Dowling, Mark Tracy, Virginia Schmied, Sally Tracy
Published in the journal ‘Midwifery’ (Link)
Review by Emma Ashworth
One of the limitations of research is getting enough data to really represent reality. This piece of research into the safety of waterbirth used data which was collected over 12 years, and considered the births of over 6,000 women. This gives us a really good, clear picture of what the outcomes really are. What the researchers have discovered is invaluable information for those looking to support women and people with their decisions around labour and birth in water compared to labour and birth on land in different positions, and supports the ongoing evidence that waterbirth is extremely safe and is an excellent way to support physiological birth.
What was the research looking at?
This research compared multiple labour and birth positions on land and in water. The aim was to see what difference six birth positions on land, and birth in water, made to perineal trauma, postpartum haemorrhage (PPH) and five minute APGAR scores.
The land birth positions were on a birth stool, semi recumbent, kneeling/all fours, lateral, standing and squatting.
Where was the research undertaken?
This data for this paper came from 12 years of maternity notes in an alongside Australian birth centre. The birth centre was next to an obstetric unit, and during the period of time that was looked at 8,338 women laboured there, and of these, 6,144 gave birth in the birth centre, the rest being transferred to the obstetric unit. Only the data of those who gave birth at the birth centre are included in this paper. The interesting thing about this birth centre is that both midwives and obstetricians work there, with the obstetricians working on a private basis, although the risk profile of the women for both types of birth workers were the same.
How accurate was the data?
The data that was used in this research paper was described as “detailed descriptions of the birth positions women had assumed for the birth as well as recording; parity, length of first, second and third stage of labour, blood loss, accoucheur, perineal trauma, sutured or not sutured, shoulder dystocia, physiological or active third stage management, use of oxytocis for third stage and analgesia.”
What were the outcomes?
- Perineal trauma
Water birth showed a lower rate of perineal trauma compared to all of the land birth positions, although only labour and birth on a birth stool reached statistical significance. The authors discuss this, pointing out that other research has shown that birth stools can lead to higher rates of perineal trauma, although a study in Sweden1 did not show this to be the case. The difference in the Sweden trial was that the women were encouraged to not stay on the birth stool for longer than about half an hour which may have lessened the risk of oedema, as oedema may be caused by sitting in the same position for long periods, and it may lead perineal tissues to be more prone to injury.
- Post partum haemorrhage (PPH)
Defined as blood loss over 1000mls, water birth led to lower rates of PPH compared to all of the land birth positions, although again only rates within the birth stool group were statistically significantly different. The authors concluded that the increased rates of PPH for those women who used a birth stool is likely to be caused by perineal damage rather than bleeding from the uterus. It is also harder to judge the loss of blood in the pool compared to in a land birth which may have led the waterbirth blood loss rates to have been under or over recorded.
- APGAR scores
The APGAR outcome that was looked at was a score of less than or equal to 7. All of the land birth positions led to more APGAR scores of less than or equal to 7 compared to water birth, although the only position where this reached statistical significance is the semi recumbent position. This may have been caused by women being asked to move into this position if there was a concern about the labour, rather than the position itself causing the lowered scores.
Although outcomes for waterbirth were better than for land birth in all areas, these differences rarely led to statistical significance. However, this does show that the outcomes of waterbirth that were looked at in this paper (PPH, perineal trauma and APGAR scores less than or equal to 7) were at least as good, if not better, than all of the land birth positions that were considered.
We can therefore conclude from the data in this paper that labour and birth in water is at least as safe as labour and birth on land, when looking at the specific parameters considered in this research paper. This is helpful to midwives and doctors wishing to demonstrate the safety of waterbirth to their Trust, and to support more midwives and doctors to be trained in supporting labour and birth in water.
- Thies-Lagergren, L., Kvist, L.J., Christensson, K., Hildingsson, I., 2011. No reduction in instrumental vaginal births and no increased risk for adverse perineal outcome in nulliparous women giving birth on a birth seat: https://bmcpregnancychildbirth.biomedcentral.com/articles/10.1186/1471-2393-11-22