The paternal sensitivity and the father-child-interaction will be measured during a five-minute-videotape of the father changing the infants' diapers and playing with the infant. The paternal sensitivity will be measured by a 9-point scale. The score can range from 1 to 9, where 1 means lack of sensitivity and 9 means very sensitive. The classification is a validated tool and is done by two trained and reliable evaluators from the Department of Developmental Science and Special Education. The evaluators are blinded.

The father-infant-interaction is investigated during the same video as the paternal sensitivity using Mannheim Rating Scales by a blinded psychologist. Mannheim Rating Scale is a good validated standardized observation instrument. Stimulation and response from the father as well from the infant are being recorded. Different communication channels can be used by father and child (vocal, facial or motor). All behaviors are analyzed at intervals of five seconds (event coding). The values are formed from the sum of the coded events. The scale ranges from 0 to 60. If there is no interaction, the scale is 0. If there is an interaction in each interval (every 5 seconds in a 5 minute videotape), the scale is 60. The father-child interaction is better if the scale is higher.

Paternal depression is assessed with the Edinburgh Postnatal Depression Scale (EPDS). It is a self-report questionnaire to measure depressive symptoms especially after birth and it consists of 10 questions. For each question the response choice are assigned point values (how often a symptom occurred during the last week). The point values are summed to a total measure score. The score ranges from 0 to 30. Zero points represents no symptoms of depression, a score of 13 or higher is interpreted to indicate a risk of depression.

There will be questions to the household income per month, the parents' highest school-leaving certificate and the housing situation

Social support is assessed with the short German version of the questionnaire on social support (F-SozU K-22). The questionnaire records the subjectively perceived or anticipated support from the social environment. There are 22 items and the test person can indicate the degree of agreement on a five-level Likert scale (from 1 = does not apply to 5 = applies completely). The scale ranges from a minimum of 22 points to a maximum of 110 points. The higher the score, the better the subjectively perceived or anticipated support.

Symptoms for post-traumatic stress is assessed with the impact of event scale - revised (IES-R). It is a self-report questionnaire and consists of 22 questions. For each question the response choice are assigned point values (how often a symptom occurred during the last week). The sub-scale values are summed by the corresponding sub-scale items. The three sub-scales are: intrusion, avoidance and hyperarousal. The overall result is calculated by a formula. The score ranges from -4,36 to 2,99. A result above 0 is interpreted to indicate a risk for post-traumatic stress disorder.

Parental Bonding is assessed with the parental bonding questionnaire (PBQ). It consists of 25 items and each item is rated on a scale from 0 to 3 points (response range from "very like" to "very unlike"). There are four sub-scales and the point values of each sub-scale are summed to a total measure score. The four sub-scales are: impaired bonding, rejection and anger, anxiety about care, risk of abuse. The higher the score, the higher the risk of a disorder in each area of the sub-scale.

Parental stress is assessed with the German form of the parenting stress index (PSI).

It consists of 48 items. The test person can indicate the degree of agreement on a five-level Likert scale (from 1 = does not apply to 5 = applies completely). There are 12 subscales, each consisting of 4 items and the points on the Likert scale are added. In each subscale there can be a minimum of 4 and a maximum of 20 points. The higher the score, the higher the parental stress.

The perceived parental stress is assessed by the German version from the perceived stress scale (PSS-10). It is a self-report questionnaire to measure symptoms of stress and it consists of 10 questions. For each question the response choice are assigned point values (how often a symptom occurred during the last month). There are two subscales (perceived helplessness and perceived self-efficacy). The subscale perceived self-efficacy are reversed score for the total score. The point values of both subscales are summed to a total measure score. The score ranges from 0 to 50. Zero points represents no symptoms of stress, higher scores reflect greater levels of stress.