Table 1.

Description of cohorts.

Descriptor	Authors
Preterm	[18,23,25,28,29]
Full term	[18,24,25,26,30,31,32,33,34]
Identical vs. dizygotic twins	[34]
Small vs. average for gestational age	[29]
Heart defects	[7]
Male vs. Female	[35]
Polluted area	[16,30]
Gestational Diabetic	[36,37]
Non-surviving	[18]