A mental case disorder? Yes, I could only think of postpartum depression or in a more serious case postpartum psychosis.
RISK FACTORS
Postpartum depression can develop after the birth of any child, not just the first. The risk increases if:
You have a history of depression, either during pregnancy or at other times
You had postpartum depression after a previous pregnancy
You've experienced stressful events during the past year, such as pregnancy complications, illness or job loss
You're having problems in your relationship with your spouse or significant other
You have a weak support system
You have financial problems
The pregnancy was unplanned or unwanted
The risk of postpartum psychosis is higher for women who have bipolar disorder.
Looking at the conditions of this woman as a first time mother at 19yrs old along with the ripening effect of her karma, it's a high possibility for postpartum psychosis resulting to killing her own baby. Some cases, mothers even kill themselves.
Below is a case of a mother who killed her 5 children due to this illness.
Andrea Yates
Andrea Yates methodically drowned her 5 children in a bathtub in her Clear Lake City, Houston, Texas house on June 20, 2001. Her mental health began to deteriorate with the birth of each of her children, combined with other external stressors. She attempted suicide twice and was hospitalized twice in a psychiatric facility in 1999 after delivering her fourth child. Yates was warned against having any more children, but conceived approximately 7 weeks later. Three months after the birth of her fifth child and shortly after the death of her father, she began to rapidly degenerate. She was hospitalized twice more, and eventually released with orders that she should not be left alone. During an hour when her husband had left for work and her mother-in-law was scheduled to arrive, she killed all five of her children. She was consequently committed to a high-security psychiatric hospital. Her case attracted a great deal of media attention, particularly to the concept of serious mental illness following (and also caused by) childbirth. Some of this coverage proved to be problematic and misleading. For example, the National Organization for Women (NOW) initially incorrectly noted on their website that Yates had suffered from postpartum depression. The Individualist Feminists quickly pointed out that Yates suffered from postpartum psychosis, a more serious and much less common disorder, and that the clinical definition of postpartum depression does not list infanticide as a symptom. This misrepresentation of Yates' illness stigmatized a large number of mothers and made them less likely to seek professional help for fear of being seen as a threat to their children and consequently being committed. NOW promptly revised their statement to indicate postpartum psychosis.
