The decision to raise a child is an important and difficult one to make: Parenthood is time-consuming and expensive. Many voluntarily childless couples choose this way of life because they want the freedom to continue pursuing their own interests. Parenthood intrudes on other domains of life: marriage and career in particular. The problem of balancing parenthood and paid work developed in several stages. Some choose full-time housework because of limited employment or child-care options. When the balance shifts because of employment opportunities, financial need, or age of children, all women reenter the labour force. Many family responsibilities disproportionately carried out by women—such as shopping for food or taking children to and from day care—require travel, and "women often travel with less efficient resources and fewer choices" than men do. Even in North America, young children can have a negative impact on personal and professional satisfaction.