The stronger the uterine contraction, the faster the birth process will be. The strength of contraction is restricted by the age of the expectant mother, muscle tone and elasticity, fetal weight and many other conditions. Pelvic size According to our usual concepts, the larger the pelvis, the greater the chance of a vaginal delivery. Medical theory also believes that expectant mothers with a pelvic diameter of more than 9.8 cm will have no problem giving birth, while those with a pelvic diameter of 9.2 cm