Digital Book Discontinued Preparing for Birth v2.4 | Page 10

4

Anatomy of Pregnancy and Birth

Understanding pregnancy anatomy will help you as you learn more about labor and birth .
placenta uterus
umbilical cord
amniotic sac amniotic fluid
Pelvic floor muscles form a multi-layered hammock that supports the internal organs and controls urination and bowel movements . During labor , they stretch to allow the baby to pass through the pelvis .
coccyx
rectum
perineum
cervix bladder pubic bone vagina / birth canal
Average Weight Gain Breakdown
Baby 6-9 lb ( 3-4 kg )
Placenta 1.5 lb ( 0.7 kg )
Uterus 2 lb ( 1 kg )
Amniotic fluid 2 lb ( 1 kg )
Breast tissue 1-3 lb ( 0.5-1.4 kg )
Blood / fluid 3-4 lb ( 1.4-1.8 kg )
Fat stores 6-8 lb ( 2.7-3.6 kg )
Total gain 25-35 lb ( 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 20 inches ( 51 cm ) in length and weighs 7.5 pounds ( 3.4 kg ).
• Most babies assume a head-down position by the time labor begins .
• Amniotic fluid surrounds the baby , providing cushion and equalizing 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 22 inches ( 56 cm ) long .
4
Labor and Birth