Preparing for Birth Australian Edition Partial Preview - Page 6

Anatomy of Pregnancy and Birth Understanding pregnancy anatomy will help you as you learn more about labour and birth. placenta uterus coccyx umbilical cord Pelvic floor muscles form a multi-layered hammock that supports the internal Preview amniotic sac organs and controls urination and bowel amniotic fluid movements. During labour, they stretch to allow the baby to pass through the pelvis. cervix Average Weight Gain Breakdown bladder Baby 3-4 kg pubic bone Placenta 0.7 kg Uterus 1 kg Amniotic fluid 1 kg vagina/birth canal Breast tissue 0.5-1.4 kg rectum perineum Blood/fluid Fat stores Total gain 1.4-1.8 kg 2.7-3.6 kg 11.5-16 kg • The uterus has grown from about the size of a pear prior to pregnancy to the size of a large watermelon by full-term. • The stomach is compressed and you may feel full after only a few bites during a meal. • Breast tissue has expanded and will begin to produce colostrum, the dense milk that will nourish baby for the first few days of life. • Blood volume has increased to about 50% more than pre-pregnancy levels. • The average baby has grown to about 51 cm in length and weighs about 3.4 kg. • Most babies assume a head-down position by the time labour begins. • Amniotic fluid surrounds the baby, providing cushion and equalising pressure. • The placenta supplies all of the oxygen and nutrients necessary for baby and filters waste products from the baby. The placenta is also the source for hormones needed to sustain the pregnancy. • The umbilical cord transfers nutrients, oxygen and fetal waste between the baby and the placenta and averages 56 cm long. 4 Labour and Birth