Every year it is estimated that about 15 million children are born preterm (before the 37 week of pregnancy). This number is increasing progressively.

Preterm birth is number one cause of death under 5 years of age.

In the world about 1 million of children die a year for that cause.

Prematurity is also the cause of increased infant morbidity. In the world the number of infant born preterm varies between 5 to 18%. (1)

4 categories of prematurity are recognized according to the gestational age in which childbirth occurs.

Extreme

0,25%

 (<28 weeks)

Early

(28-30 weeks)

about in 0.25% of pregnancies

Moderate

(31-33 weeks)

about in 0.6% of pregnancies

Mild

 (34-36 weeks)

about in 0.3% of pregnancies

In Italy the percentage of preterm birth is around 8%.

It is now known that preterm birth depends on two major causes.

1.

2.

The first is the predisposition to preterm birth that is genetically set and gives rise to the condition that today we define spontaneous preterm birth.

The second is related to a series of clinical causes and concauses that can determine preterm birth even in subjects that are not intended. These conditions obviously aggravate and anticipate the event of birth in those genetically predisposed.

TAB. 1 Traditionally recognized causes of preterm birth

A

SOCIO-DEMOGRPHIC FACTORS (*)
  • Maternal age (older women shorter pregnancies)
  • Marital Status
  • Economic and social condition
B PREGRAVID MEDICAL CONDITIONS
  • Genital malformations
  • Autoimmune diseases
  • Pulmonary, renal and cardiac pathologies
  • Hyperthyroidism, diabetes, hypertension
C GRAVID CONDITIONS
  • overstretching of the uterus for multiple pregnancy (overexpression of the gap-junction) or Polyhydramnios (prostaglandin and oxytocin receptors)
  • Pregnancy after Assisted Reproductive Technology
D BIOLOGICAL CONDITIONS
  • Pre-activation of the “placental clock” through the hypothalamic-pituitary-adrenal axis (HPA) for different stresses
  • Infections and inflammation of the genital tract (cascade cytokines and prostaglandins) and systemic (Matrix metalloproteinase activation)
E ENVIRONMENTAL TOXIC CAUSES(*)
  • Air pollution
  • Agricultural pollution
  • Polychlorobiphenyls and dioxins
  • Metal and metalloid pollutants
F INFLUENCE OF PERSONAL CONDUCT (*)
  • Cigarette smoke
  • Abuse (alcohol and drugs)
  • Nutrition
  • Work, physical and sexual activity
  • Personal hygiene
* with significant variations and differences between races and populations