About five percent of the calves at birth are in abnormal positions, such as foreleg or head turned back, breech or rear end position, sidewise or rotated, etc. This requires the assistance of a veterinarian or an experienced herdsman to position the fetus correctly prior to delivery. If fetal position cannot be corrected, the veterinarian may have to perform a caesarean section. The time interval of each stage varies among types and breeds of cattle and among individuals of the same breed. Although the exact stimulus that initiates parturition is unknown, it does involve hormonal changes in both the cow and fetus as well as mechanical and neural stimulation in the uterus.
Calf rotates to upright position.
Uterine contractions begin. Water sac expelled. Cow usually tying down. Fetus enters birth canal. Front feet and head protrude first.