Jill used a substance during her pregnancy that is known to harm the fetus. jill’s baby was born shorter and lighter than average, has poor respiratory functioning, and tends to be colicky. the substance jill probably used is:

The substance that the mother probably used is nicotine.

Explanation:

When a pregnant woman smokes it can cause the baby to have difficulty with their respiratory function, low birth weight, and be shorter than average babies. Many of the babies born by a smoking mother does have colic.

The mother can suffer from pregnancy complications if she has been a smoker.

Smoking while pregnant, can also cause issues with the baby's brain. It is important to not smoke while you are pregnant. If a person smokes and finds out they're pregnant, they should stop immediately.