Fetal position at the onset of labour is one of the greatest determining factors of how the birth process will proceed. During labour the fetus makes certain movements to descend through the pelvis. The optimal fetal position is pictured below. A good way to remember the best position is to think about giving your baby a back rub every time you rub your belly.
A spot near the back of the fetal head is used to determine fetal position. The terms “posterior” or “sunny-side up” describe a baby who faces out, or is spine-to-spine with mother. “OP” is the medical jargon. The presenting part of the head is bigger in this position and the baby doesn’t flex and rotate as well as an anterior baby.
Problems Related to Posterior Position
- More difficult for baby to drop into and through the pelvis
- Pregnancy may last longer
- Membranes are more likely to rupture before the onset of labour
- Labour may progress slowly or not at all
- Back-pain during labour that doesn’t disappear between contractions
- Increased risk of tearing
- Increased risk of instrumental or surgical birth
- Increased stress on baby’s head and nervous system
However some women birth a posterior baby just fine. Those include but are not limited to, women who’ve given birth without difficulty before, those with an average or smaller baby, a labouring woman who’s able to move about freely and allow her baby to rotate into an anterior position.
Baby in optimal position: head down and flexed, back out.
Signs of a Posterior Baby
- Feeling kicks or flutters at your front
- Frequent urination (more frequent than with anterior pregnancy)
- Belly appears flat or lumpy
- Your midwife or doctor can tell by palpating your abdomen, as is done at every prenatal visit
- Fetal heart-tones may be difficult to hear
- Head is not engaged or doesn’t drop into pelvis
- Can be confirmed with ultrasound
- During labour she can also tell during an internal examination
Factors Contributing to Posterior Position
Posterior-babies can occur with no risk factors, but the following increase the chances:
- North American lifestyle – reclining in upholstered furniture, sedentary lifestyle, sitting in cars (it’s interesting to note this position is rare in cultures where women walk a lot or work bent-over, and lack Lazy-Boy style chairs and couches)
- Sitting with legs crossed
- Postural or anatomical issues
- Issue of uterine / abdominal muscles (e.g. tight psoas)
- First pregnancy
- Epidural use early in labour (hinders rotation and descent of baby) is correlated with more than 3x the rate of posterior position at birth (Tully, 2008)
- Labouring in bed or without adequate movement
- Baby who was breech and turned to vertex
- Mother with history of breech or posterior baby
- Short or tight cord around baby
- Emotional issues – fear of birth or parenting, not paying attention to pregnancy, family history of breech, relationship issues, financial concerns, stress (Frye, 1998)
Tricks for Turning a Posterior Baby to an Anterior Position
Sometimes there’s a reason (that we don’t know about) for baby to be posterior and nothing will turn her or him. But in many cases a baby can be turned. Please ask for details or referrals.
- Visualization and “talking” to your baby. Focus on letting the baby know it’s easier to get out when facing the other way. This works especially well if combined with changing your emotional environment e.g. dealing with fears, prepping for birth.
- Look at a picture of baby in proper position (e.g. Fig. 1), or have it drawn on your belly!
- Webster Technique with a chiropractor certified in its use. Pistolese (2002) cites an 82% rate of success in relieving the musculoskeletal causes of intrauterine constraint. It’s beneficial to perform the Webster Technique starting at 35-36 weeks.
- Sit with pelvis tilted forward – knees below pelvis with straight back. Instead of upholstered furniture, use a birth ball, the floor, a kneeling chair or a regular hard chair or stool
- Hands and knees – read, crawl around, or child’s pose modified for pregnant belly
- Pelvic rocking while on all 4’s – gentle cats and dogs yoga postures – several times daily
- Swimming or floating – anything with belly down like a hammock for baby to drop into
- Movement and exercise
- Sleep on left side with a body pillow – left leg straight, right leg bent on pillow
- Keep belly warm (babies may turn back to keep warm against mother’s back)
- Homeopathic Pulsatilla 200CH, 1 dose every 3 days.
- Acupuncture or moxibustion – see a Traditional Doctor of Chinese Medicine or an acupuncturist who specializes in women’s and pregnancy care.
- Deal with fears around childbirth and parenting
- Postural management – check out spinningbabies.com for some excellent postures and exercises that encourage babies to assume optimal positions for birth.
Frye, A. (1998). Holistic Midwifery, Vol 1, Care During Pregnancy. Portland, OR: Labrys Press.
Ohm, J. (2006). About the Webster Technique. Retrieved from icpa (International Chiroractic Pediatric Association): http://icpa4kids.com/about/webster_technique.htm
Pistolese, R. (2002). The Webster Technique: A chiropractic technique with obstetril implications. Journal of Manipulative and Physiological Therapeutics , 25 (6), E1-E9.
Tayler, R. (2000). Homeopathy for Pregnancy and Childbirth. Ottawa: Ottawa School of Homeopathy.
The Midwifery Group. (2008). Posterior Babies. Retrieved from The Midwifery Group: http://www.midwiferygroup.ca/downloads/position/Posterior%20Babies.pdf
Tully, G. (2008). Occiput Posterior – OP. Retrieved from Spinning Babies: http://www.spinningbabies.com/baby-positions/posterior