There was a time when the U.S. legal system would want or tend to put children under the custody of the mother. As time has changed, the court is always trying to put the child's best interest in mind. They want to make a decision based on what the best outcome for the child will be. In order for a mother to gain full custody of her children, she will have to prove that a different decision would negatively affect the children. This is often viewed as the case if the other parent is not involved in their child's life.
The laws vary by state so it is important to take this into consideration. You will definitely want to check with your state's specific laws. Your state will determine the custody arrangements available to you. Most states will use the best interest of the child standard to make a decision. The court will look at different factors such as the age of the child, their specific needs, and each parent's ability to take care of the child. They will want to see if there is any history of abuse or neglect from either parent. This would be a reason why a parent will not receive custody rights. A court may also look at the existing bonds between a child and a parent. They will always want to put that child in a situation where they are most stable.
It's important to consider the difference between sole and joint custody. Sole custody will allow a parent the complete custody of a child. Joint custody is when both parents have legal custody of the child. A couple with joint custody will have particular custody agreements.
Often parents may want to work out a situation without the need to go to court due to the lengthy process, as well as because they don't want to spend a lot of money. They may make a decision between the two of them about who the child is better off living with. If parents cannot come to a decision then mediation can often solve this issue.
If you are a mother trying to gain sole custody of your child, there has to be a reason for it. You must believe that otherwise your child would be in a dangerous or negatively impacting situation. Usually a mother will win full custody if the child is in a situation where the other parent is abusive, is involved in criminal activities, or if that parent is never around.
Source: Legal Zoom