The endometrium is the innermost layer of the uterus that contains the lining which is responsible for accepting and nourishing a fetus during the pregnancy process. The lining of this cavity changes with every monthly cycle in response to the primary female hormones produced by the ovaries: estrogen and progesterone.
If one parent is more stable than the other, judges can decide to award primary custody to that parent. As a result, parental fitness is often a mechanism used in custody battles. Each state has its own set of rules regarding what makes a parent unfit.
Emergency custody of children is often sought if one parent becomes abusive and presents imminent harm or threat to the child. Other instances include child abandonment or parental substance abuse that puts the child in danger.