Oops. Upright birth positions increase bleeding and perineal trauma.

Yesterday I wrote about the efforts of Lamaze to control women’s births. The irony, of course, is that the practices that they staunchly advocate are not supported by, and in some cases are even directly contradicted by the scientific evidence. Such is the case with upright birth positions.

It is axiomatic among natural childbirth advocates that maternal position dramatically impacts the course of labor. Yet, there’s no scientific evidence that moving around or changing positions has any impact on labor, let alone a beneficial impact. According to the Cochrane review on position in labor, “There were no differences between groups for other outcomes including length of the second stage of labour, mode of delivery, or other outcomes related to the wellbeing of mothers and babies.”

Indeed it is appears that upright positions, far from being beneficial, actually increase the risk of bleeding and perineal trauma. Dutch author de Jonge (the same de Jonge who conducted the large trial demonstrating the safety of homebirth in the Netherlands) reached this conclusion in the paper Increased blood loss in upright birthing positions originates from perineal damage published in the British Journal of Obstetrics and Gynaecology in 2007.

According to de Jonge:

The main advantage of the supine position is reduced mean blood loss and incidence of blood loss greater than 500 ml compared with other positions…

Measurement error may explain some of the differences found. The same amount of blood loss may appear to be more in upright than in recumbent position. In most studies, estimated blood loss is used as the outcome measure. We wanted to improve upon previous research and establish whether there is an actual increase in blood loss in sitting positions by using more accurate, objective measurements.

If there is a real difference, it is not clear whether this excess in blood loss originates from perineal damage or from the uterus… If there is an increase in blood loss in sitting positions, it is therefore important to establish where this originates from.

The study found:

The mean blood loss in the total group was 508 ml. Blood loss greater than 500 ml occurred in 38.5% and greater than 1000 ml in 9.1% of women. In semi-sitting and sitting position, the mean total blood loss was significantly greater than in recumbent position. A significant linear association was found for the following variables: the risk of blood loss greater than 500 ml and 1000 ml was greater in semi-sitting than in recumbent position and greater in sitting than in semi-sitting position.

In other words, position affected blood loss in a linear fashion. Women who were semi-sitting had a higher blood loss than women who were lying on their backs and women who were upright had a higher blood loss than those who were semi-sitting.

Since the blood loss came from the perineal damage, women who delivered without lacerations were not affected. However, position appeared to have no impact on perineal damage:

The incidence of perineal damage did not differ between position groups. Thirty-one women had a third or fourth degree tear, and the incidence did not differ between the groups (P = 0.656).

The authors speculate that increased blood loss is related to increased hydrostatic pressure in the lower half of the body (the same factor that leads to hemorrhoids and varicose veins in pregnancy):

The increased blood loss in upright positions may be due to various factors. Sitting on the hard surface of a birthing stool or chair may obstruct venous return and therefore lead to an increase in blood loss from perineal damage. On the other hand, upright positions might cause increased hydrostatic pressure both on the arterial and venous side which could contribute to increased bleeding from the uterus and placental site…

It is also possible that increased hydrostatic pressure leads to perineal edema (swelling) and that the edema leads to lacerations and difficulty in controlling the blood loss by suturing.

de Jonge re-analyzed this data in a paper published earlier this year. She and her co-authors investigated why there was no difference in perineal trauma among different positions. What they found lends credence to the original rationale for episiotomies. Women in upright positions had fewer episiotomies, but more perineal tears. The perineal damage was not reduced in the absence of episiotomy either; the incidence of 3rd and 4th degree tears was the same regardless of position. In summary, there was no protective effect on the perineum of upright positioning.

So upright positions in labor have no beneficial effect on the course of labor and no beneficial effect on the incidence of perineal trauma. In fact the only difference directly attributable to upright position is a disadvantage: a statistically significant increase in blood loss.

Is that a reason to discourage upright positioning? de Jonge doesn’t think so and I don’t either. Women should be encouraged to labor and deliver in the position most comfortable for them. For some women that will be lying down, for other women a more upright position is preferable. One thing is not in doubt, however. There is no benefit to upright position in labor, and Lamaze and other natural childbirth organizations should stop pretending there is.