In the past, a pregnant woman could expect her doctor to measure her feet as this measurement was used to assess her likelihood of needing a caesarean section. Small feet were seen to indicate a narrow pelvis.
There is some truth in the fact that small feet generally indicate that a woman is small-framed and therefore likely to have a small pelvis. However, small women tend to grow small babies which are in proportion with their pelvic size. True cephalo-pelvic disproportion (CPD), where the baby’s head is too large to fit through the pelvis and be born vaginally, is relatively rare.
There are other important facts to consider in this situation:
- The pelvis is not a fixed structure. The pregnancy hormone relaxin helps to soften the ligaments which hold the pelvic bones together and this helps the pelvis to stretch to accomadate the baby.
- A baby’s head is designed to mould into shape. The skull is made up from separate bones which are able to overlap each other slightly in order to reduce the overall size of the head as it travels through the pelvis during labour. This is a normal part of the birth process.
- The positions that a woman adopt during labour and birth affect the dimensions of the pelvis. For example, squatting can increase the internal measurements of the pelvis by around 30%. Sitting, or lying on your back can actually reduce these measurements by restricting the natural backwards movement of the tailbone (coccyx) during birth.
- The position of the baby is also important and can make the difference between a straightforward birth and one that is difficult. For example, if the baby is in a ‘back to back’ position (occipito-posterior), it makes navigation of the pelvic canal much complicated. For information on how to encourage your baby into the best position for birth, see: http://www.homebirth.org.uk/ofp.htm1
During labour, the midwife caring for you will be regularly assessing the progress of your labour not only by checking how your cervix is dilating, but checking the baby’s position and descent through the pelvis. If there are any concerns, she would refer you to a doctor on duty who would help assess the situation and decide on a plan of action. Sometimes, if progress is not being made, an assisted delivery is necessary whether in the form of forceps/ventouse or a caesarean section. This can occur regardless of the woman’s shape or size.
1 Norowitz, E 2006: “Obstetrics and Gynaecology at a Glance”