Early childhood can be a stressful period for families with a significant impact on parents' mental health, the child's healthy development, and the development of a secure mother-child attachment. The goal of the cross-sectional study part of SKKIPPI was to assess the occurrence of psychosocial stress and mental health disorders in parents as well as in their offspring in early childhood in three German regions. Based on random samples from three residents' registration offices, parents with infants aged up to 12 months were invited to participate. An online screening questionnaire was developed in four languages to assess common psychosocial stressors and mental health problems of parents with small children. The study enrolled 4984 mothers and 962 fathers. The most common potential psychosocial stressors were professional problems (mothers 22%, fathers 33%), lack of social support (20%, 14%), and severe, negative experiences in childhood (22%, 16%). Obsessive-compulsive thoughts (21%, 16%) and depressive (9%, 9%) and anxiety symptoms (11%, 7%) were the most frequently reported mental health problems by both parents. Regulatory problems of the child were reported by between 1.5% and 5.1% of parents. The study showed that a substantial proportion of parents are burdened by psychosocial problems and suffer from mental health problems in the first years after the birth of their children. Early preventive and low-threshold support measures should be available in the health and social care system. Low-threshold questionnaires, which cover a wide range of possible stress factors, should be further developed for the practical healthcare of this group of people.