[Birth characteristics due to in vitro fertilization (IVF) techniques]

Abstract

Objective: To determine the number of deliveries after 31 weeks gestation (w), from in vitro fertilization (IVF), including Intracytoplasmic Sperm Injection (ICSI), and to compare characteristics with those achieved by natural fertilization (NF). We analyse twin and singleton pregnancies separately.

Patients and method: This descriptive and prospective study monitors children from foetus, from 12 weeks after IVF, to 12 months of age, including the newborn period. There were 7008 newborns between 1st January 2004 and 31st March 2007 of which there were 113 from IVF and 6895 from NF.

Results: Twin-pregnancies in NF is 2.4%, whereas in IVF it is 56.6%, (p<0.001). Mean mother age is 28+/-9 years (y) in NF and 36+/-4y in IVF singletons (p<0.05), and 29+/-10 y in NF and 35+/-4 y in IVF twins (p<0.05). Mean gestational age is 38+/-4 w and 39+/-2w in NF and IVF singletons and 36+/-1 w in NF and IVF twins. No statistically significant differences were found in prematurity rate (<37 w) and low birth weight (< 2500g) between singletons and twins from IVF or NF. Caesarean sections were 23.13% and 51.02% from singleton NF and IVF (p<0.001). No statistically differences were found between twins NF (71.42%) and IVF (79.69%). Malformations at birth were observed in 5.3% of IVF and in 1.1% of NF newborns (p<0.002). Relative risk of malformations (RR) IVF versus NF is 4.83 (95% CI, 2.14-10.83).

Conclusions: Only 1.61% of newborns comes from IVF techniques. There are significant differences in age of mother, twin- pregnancies, caesarean sections (singletons) and congenital defects between them and NF newborns. There were no differences found in prematurity and low birth weight between them and NF newborns, when compared by number of foetus.