Childbirth is a succession of mechanical and physiological processes during which five elements of pregnancy are released vaginally. These elements include fetus, placenta, umbilical cord, fetal membranes and amniotic liquid. The process of labor and birth is divided into four stages. This paper deals with irregularities of second childbirth. The second stage is the process of fetal expulsion. The complications that arise as the consequences of irregularities of fundamental factors in birth are as follows: irregular contractions, birth canal, irregular posture, rotation and position, as well as birth traumas. Occipitoanterior position of an infant in mother’s pelvis just before the birth is ideal for birth. Toward the end of pregnancy, the fetus moves into the most common position for delivery, occipital anterior, which means that fetus is head down, facing mother’s back. This position is ideal for birth as it eases the delivery through the birth canal. Several other (irregular) positions of an infant may occur and they may lead to prolonged delivery or birth traumas. Birth traumas are mostly riskless, cause no permanent consequences and thus, there is no need for therapeutic procedures. However, some birth traumas may occur and the most common ones are subcutaneous haemorrhage, clavicular fracture, cephalhematoma, transitory facial nerve damage (nervus facialis) and brachial nerve damage (nervus brachialis). A mother may have birth traumas such as perineal rupture (ruptura perinei), vulvar rupture (ruptura vulvae) and uterus rupture (ruptura uteri).