The deaths occurred across the country between December 25th and 31st.
While all appear to have explicable causes, their concentration over the holiday period has raised questions over whether hospital staffing may have been a factor and also over whether older mothers-to-be are being sufficiently monitored for warning signs of potentially fatal conditions.
In the latest case, Giovanna Lazzari, 29, already a mother of two who was eight months pregnant, died on New Year's Eve in Brescia, northern Italy, a day after coming to the clinic's emergency unit with a high fever and symptoms of gastroenteritis, according to her partner Roberto Coppini.
As her condition deteriorated, doctors attempted an emergency Cesarean but were unable to save either the mother or the foetus.
"In a few hours, I lost a baby and a unique mamma. Someone has to tell me what happened," Coppini told reporters.
"Giovanna sent me a text message during the night in which she told me she had very strong pains but that the doctors were not paying any attention to her."
"She would have been 30 on January 1. She was young and healthy."
Health minister Beatrice Lorenzin has dispatched a team of experts to try and establish what happened in the Brescia clinic and three of the other four fatal cases.
"We have to understand if the recommended procedures were followed or if there were organisational deficiencies," Lorenzin said.
"The priority is identifying any errors and preventing other tragedies."
According to media reports, the tragedy in Brescia was triggered by a detachment of the placenta from the wall of the patient's uterus.
In two of the other cases, both of which resulted in still births, the mothers, aged 35 and 39, suffered cardiac arrests during labour, according to reports.
Anna Massignan, a 34-year-old doctor from Lonigo, near Vicenza who died on Christmas Day, succumbed after an emergency Cesarean eight months into her pregnancy, reportedly following a fall at home. Her son was delivered alive but died several hours later.
The one case not being investigated concerned a 23-year-old from Foggia in southern Italy who was approaching her due date and died suddenly at home. Doctors were able to perform a post-mortem Cesarean and save her daughter.
- 'Obsolete procedures' -
Although the tragedies being investigated all appear to be explicable, a leading gynaecologist said some of the victims may have paid the price for inadequate screening for the risk of thrombosis or heart problems emerging during the latter stages of pregnancy.
"With preventative checks we could save so many women in the delivery room," said Rosalba Paesano, Professor of Gynaecological Science at Rome's La Sapienza university.
"But the health ministry does not say they are required, in reality because they cost too much. The procedures we have in place are obsolete," Paesano told La Repubblica.
Antonio Starita, medical director at Rome's San Camillo hospital, told La Stampa: "The one figure that stands out is that 35 percent of pregnancies in Italy involve women over 35 and, at this age, the maternal mortality risk doubles."
Starita said blocks on new hires in parts of the health system could be creating staff shortages, particularly amongst midwives assigned to home visits who could pick up early warning signs of problems in a pregnancy.
According to World Bank figures, Italy has had an average of four childbirth related maternal deaths per 100,000 live births since 2004, making it one of the top ten safest countries for women having a baby.