Introduction A certain amount of oxidative stress has a role in the normal progression of embryonic and fetal growth, as well as during labour. In contrast, increased OS has been involved in the causation or worsening of several gestational, fetal and neonatal diseases. Cell lipid peroxidation by free radicals causes membrane lipid disruption and is potentially harmful. Malondialdehyde (MDA) is one of the end products of lipid peroxidation, which can be interpreted as a marker of the extent of damage to cells and the anti-oxidative system capacity.

Objective As part of a study on oxidative stress on the term newborn, we aimed to determine the baseline levels of MDA in blood and urine of healthy term newborns.

Patients and methods All newborns above 35 gestational weeks born in our institution from October 2012 – March 2013 were eligible for study. Newborns with potential risk factors for increased oxidative stress were excluded for this analysis. Blood samples at birth (cord arterial and venous blood) and at 48 h postnatal life (heel puncture) were collected. Urine from the first and second day was collected.

Results 204 newborns (90 females and 114 males) met the inclusion criteria. Reference MDA levels were as follows (µM, mean ± SD): cord vein 3.37 ± 1.16; cord artery 3.33 ± 0.94. At 48 h postnatal life, 3.29 ± 0.91. Urinary levels were as follows: first day urine 1.24 ± 0.87; second day urine 1.48 ± 0.99. There were no statistical differences between males and females.

Conclusions These are data from a large group of newborns, aiming to give an accurate description of the baseline levels of malondialdehyde in our population, which could be useful when it comes to making therapeutic decisions in the future.