Here are the stages of pregnancy as detected by palpation.

70 days – The enlarging uterus is readily felt. The amnion sac feels like a solid oval ball (about 2¼ in. in diameter) floating within it.
90 days – The uterus is usually still resting up near the pelvic brim, with the pregnant horn about 3½ in. wide and the nonpregnant horn about 2 in. wide. The fetus can sometimes be felt in the pregnant horn.

110 days (3½ months) – The enlarging uterus has dropped below the pelvic brim (the cervix lies at the brim) and there is fluid distention in the lower part of the uterus.

4-5½ months – It is possible to feel the fetus in about half the cases.

5½-7½ months – It’s more difficult to reach the uterus, but if so, you may be able to touch the fetus’ head or flexed limbs that lie just beyond the pelvic brim.

7½ months to birth – It’s often easier to feel the fetus because it’s grown so much that the front legs are closer to the pelvis. If you can’t reach the uterus, you may be able to feel large cotyledons or a strong vibrating pulse in the enlarged uterine arteries.

Age-old methods

Seeing a cow in heat is usually a clue she’s open, but it’s not a dependable way to determine pregnancy. Some open cows don’t cycle if they’re lactating or have a cystic ovary, and some pregnant cows will continue to show heat.

Old-timers used a few other ways to determine pregnancy. Some say you can feel the fetus by about the fifth or sixth month by putting your hand against the cow’s lower flank and making a quick upward and inward push. If she’s pregnant, the fetus should bounce back against your hand.

Another method sometimes used was to milk a little from the cow just after the calf is weaned and put a drop of milk into a glass of water. Proponents of this method claim that if the drop goes all the way to the bottom without spreading out, the cow is pregnant; if the milk droplet spreads out, she’s open.

One other thing noticed by many stockmen is that after you work the herd in the fall and wean the calves, many of the open cows that weren’t cycling during lactation will come into heat shortly after you pull their calves off.