The average length of pregnancy in goats is 150 days, or five months. During early pregnancy, embryonic losses are usually 20 to 30 percent higher than in later pregnancy. There are a number of external factors that can cause pregnancy losses, including environmental stress caused by heat, nutrition, or even doe age. During early pregnancy, the kid is just an embryo and it is also extremely sensitive to a wide range of drugs and mineral deficiencies.
During pregnancy in goats, high levels of progesterone from the corpus luteum on the ovary help inhibit uterine contractions until kidding and helps support the pregnancy in general. Spontaneous (non-infectious) abortions (miscarriages) resulting from low progesterone are more common in goats than sheep (the placenta also produces supplemental progesterone in sheep). Under-nutrition, vitamin and mineral deficiencies, toxic plants and certain drugs such as levamisole can contribute to non-infectious abortions. Multiple late abortions ('abortion storm') usually suggest an infectious source such as chlamydiosis or toxoplasmosis or others. To properly diagnose the cause of an infectious abortion, the fetus, portions of the placenta and a blood sample from the doe should be collected for testing. Your veterinarian should be consulted with multiple, especially late-term (late pregnancy), abortions. State diagnostic laboratories or your veterinarian should be able to help with testing for abortions.
For more information about feeding during pregnancy see: http://www.extension.org/pages/19333/goat-nutrition