Maternal Position and Other Variables: Effects on Perineal Outcomes in 557 Births. Meyvis I, Rompaey BV, Goormans K, Truijen S, Lambers S, Mestdagh E, Mistiaen W BIRTH 39:2 June 2012

Trisha Jenkyns 8-8-12

Primary Aim: To investigate the effect of the maternal position (lateral vs lithotomy) and other variables (demographic characteristics, gravidity, parity, duration of pregnancy, reason for admission, and mode of labor) on perineal outcomes or the occurrence of perineal damage

Study Design:  retrospective cross-sectional design

Methods:

Hospital records were collected & examined from a regional hospital in Belgium from November 2008 to November 2009 of all women (between 37 and 42 weeks gestation) who were delivering vaginally.  Exclusion criteria: premature delivery & any kind of operative delivery because these conditions could necessitate episiotomy.

 Definitions: Lithotomy & lateral sidelying are defined as horizontal positions for birth.  The distinction between horizontal & vertical are defined.  Horizontal is as an angle of less than 45° between the horizontal & the birth canal and vertical is the same angle but greater than a 45° (i.e. squatting, sitting, and standing).

Perineal outcome/damage was graded according to Fernando.

Grade 1 refers to a tear limited to the skin or vaginal wall.

Grade 2 involves the perineal musculature as well

Grade 3 involves damage to the anal sphincter.

Episiotomy is defined as a medio-lateral incision widening the birth canal. Lacerations occurring after an episiotomy were classified as episiotomy + laceration.

 Results

·         A total of 1,016 women gave birth in the Belgium hospital, 557 were included

o   348 women delivered in the lithotomy position

o   209 women delivered in the lateral position.

·         Data collected: Age, marital status, origin, gravidity, parity, gestation, birth weight, duration of admission, reason for admission, medication, birth attendant, epidural analgesia

o   Only 2 factors differed significantly: women in the lateral position were older and less likely to have epidural anesthesia than those who delivered in the lithotomy position.  Otherwise the 2 groups were similar in demographics, etc

·         The effect of position on perineal outcome was studied with and without episiotomy (perineal damage is described as a percentage):

1.    The lateral position showed significantly more lacerations (1^st & 2^nd degrees) than the lithotomy position.

2.    Episiotomy was performed significantly less frequently in the lateral position.  Episiotomies were used in 38.2 % in lithotomy position and in less than 7 % in lateral position.

3.    Including both laceration and episiotomy in the analysis, an intact perineum was significantly more likely in lateral position (45.9% vs 27.8%).

4.    The difference in the effect of position on perineal outcome became insignificant on excluding participants with episiotomies.

·         The incidence of episiotomy differed according to type of birth attendant:

·         Primiparas underwent an episiotomy more frequently: 53 percent (n = 85)

had episiotomies and 19 percent (n = 30) had an intact perineum after delivery

·         Multiparas underwent significantly fewer episiotomies (17%; n = 68) and more lacerations

·         In women without perineal damage, parity was significantly higher (2.0 ± 1.0 vs 2.8 ± 1.4, p < 0.001)

·         Differences in birthweight and in the weight/length ratio of the newborn had no significant effects on perineal outcomes

·         A multivariate logistic regression analysis showed the protective effect of the lateral position and parity against perineal damage.

·         Logistic regression showed that a one-child increase in parity decreased the likelihood of perineal damage by 44 percent.

·         There was a 47% decrease in perineal damage with the lateral position. 

·         In contrast, delivery by a physician (compared with a midwife) and the use of epidural analgesia resulted in a considerable increase in perineal damage.

Discussion

·         Perineal damage decreased significantly for deliveries in the lateral position.

·         Almost 50 percent of women delivering in the lateral position had an intact perineum, compared with one-third of those delivering in the lithotomy position.

·         Midwives perform fewer episiotomies than physicians

·         For the lateral position, fewer episiotomies were performed, but perineal lacerations of grades 1 and 2 were significantly more common.

·         In contrast to the lithotomy position, delivery in the lateral position is a “hands-off” technique, avoiding unnecessary manipulations, which could explain the low number of episiotomies.

·         Births assisted by midwives; almost 60 percent of the women had an intact perineum

·         Midwives used episiotomies for only 2 percent of the women.

·         More variation occurs among physicians in use of episiotomies: over 30% use episiotomies…with one physician doing an episiotomy in 76 percent of all women.

·         Even with exclusion of episiotomy, a trend toward less perineal trauma was observed for the lateral position.

·         In contrast to other studies birth-weight and the weight/length ratio of the newborn had no effect on perineal damage.

Limitations

·         Other factors to include: baby’s head size (biparietal diameter), duration of pushing. A prospective study would be VERY illuminating!

 Clinical Application

·         How much do you talk to your patients about birthing positions? Participants stated they do not usually recommend specific positions based on pelvic floor considerations.

·         Comments made:

o   Knowing baby’s position in utero can help determine the maternal position

o   We know epidurals can slow things down and maybe this was more related to the reason for episiotomies

o   It is likely that different positions work differently for each woman

o   It makes sense to consider position, but this is only one variable when looking at  perineal outcome.