Separation anxiety disorder (SAD) is an anxiety disorder in which an individual experiences excessive anxiety regarding separation from home and/or from people to whom the individual has a strong emotional attachment (e.g., a parent, caregiver, significant other, or siblings). Separation anxiety is a natural part of the developmental process. It is most common in infants and little children, typically between the ages of six to seven months to three years, although it may pathologically manifest itself in older children, adolescents and adults. Unlike SAD (indicated by excessive anxiety), normal separation anxiety indicates healthy advancements in a childs cognitive maturation and should not be considered a developing behavioral problem.According to the American Psychiatric Association (APA), separation anxiety disorder is an excessive display of fear and distress when faced with situations of separation from the home and/or from a specific attachment figure. The anxiety that is expressed is categorized as being atypical of the expected developmental level and age. The severity of the symptoms ranges from anticipatory uneasiness to full-blown anxiety about separation.SAD may cause significant negative effects within areas of social and emotional functioning, family life, and physical health of the disordered individual. The duration of this problem must persist for at least four weeks and must present itself before a child is eighteen years of age to be diagnosed as SAD in children, but can now be diagnosed in adults with a duration typically lasting six months in adults as specified by the DSM-5.
Most commonly from Ureaplasma, Fusobacterium, and Streptococcus bacteria species. Less commonly, Gardnerella, Mycoplasma, and Bacteroides bacteria species. Sexually transmitted infections, chlamydia and gonorrhea, can cause development of the condition as well. Studies are continuing to identify other microorganism classes and species as infection sources. Obstetric and other
Birthing-related events, lifestyle, and ethnic background have been linked to an increase in the risk of developing chorioamnionitis apart from bacterial causation. Premature deliveries, ruptures of the amniotic sac membranes, prolonged labor, and primigravida childbirth are associated with this condition. At term mothers who experience a combination of pre-labor membrane ruptures and multiple invasive vaginal examinations, prolonged labor, or have meconium appear in the amniotic fluid are at higher risk than at term mothers experiencing just one of those events. In other studies, smoking, alcohol use and drug use are noted as risk factors. Those of African American ethnicity are noted to be at higher risk. Anatomy
The amniotic sac consists of two parts: 

The outer membrane is the chorion. It is closest to the mother and physically supports the much thinner amnion. The chorion is the last and outermost of the membranes that make up the amniotic sac. The inner membrane is the amnion. It is in direct contact with the amniotic fluid, which surrounds the fetus. The amniotic fluid exists within the amnion, and is where the fetus is able to grow and develop.