Physical health of singleton children born after frozen embryo transfer using slow freezing: a 3-year follow-up study

STUDY QUESTION

Are there differences in the physical health of singleton children born after frozen embryo transfer (FET) compared with children born after fresh embryo transfer (fresh ET)?

SUMMARY ANSWER

Register-based health indicators were similar among FET and fresh ET singletons during a 3-year follow-up.

WHAT IS KNOWN ALREADY

Large cohort studies have shown that perinatal outcomes are similar or even better in FET than fresh ET children. The early childhood morbidity among FET and fresh ET children has been shown to be quite similar, but so far these studies have been small. The short-term health outcomes of assisted reproductive technology (ART) children have been shown to be slightly worse compared with spontaneously conceived children.

STUDY DESIGN, SIZE, DURATION

This register-based study includes women who had undergone ART treatments leading to singleton live births (n = 4758 children) in 1995-2006. A 10% random sample of women with spontaneous pregnancies from the Finnish Medical Birth Register (FMBR) served as the reference group (n = 31 137 children). The children were identified through the FMBR by using the mother's personal identification (ID) number. Children's ID numbers were linked with two nationwide registries; the Finnish Hospital Discharge Register and the Cause-of-Death Register at Statistics Finland. Information on all visits was received until 2009 using ICD-10 codes.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study includes 1825 children born after FET, 2933 children born after fresh ET and 31 137 children born after spontaneous pregnancies. The risk estimates for diseases were adjusted for the child's year of birth and maternal age, parity, socio-economic status and prematurity. The study focused on the differences between FET and fresh ET children.

MAIN RESULTS AND THE ROLE OF CHANCE

Most health indicators were similar among FET and fresh ET children during the 3-year follow-up. The most common discharge diagnoses, including gastroenteritis and colitis, otitis, upper and lower respiratory diseases, asthma and allergies were similar between the ART groups. A large proportion of FET children (70.1%) and fresh ET children (69.9%) had visited a hospital at least once (P = 0.877). The risk of hospital admission did not differ between the two groups after adjusting for premature births [adjusted odds ratio (aOR) 1.01; 0.88-1.17]. Comparing with children born after spontaneously conceived pregnancies, the risk of hospital admission was slightly increased in the ART group, even after adjusting for premature births (aOR 1.10; 1.02-1.19).

LIMITATIONS, REASONS FOR CAUTION

Due to the study design, we were not able to control for some parental background factors, such as the cause and length of infertility. Furthermore, the health registries do not include data on the growth of the children. Our findings are generalizable only to the slow-freezing method.

WIDER IMPLICATIONS OF THE FINDINGS

Our study provides further evidence of the safety of embryo cryopreservation. The early physical health of FET children is similar to that of children born after fresh ET.

STUDY FUNDING/COMPETING INTERESTS

This study was funded by the University Hospital of Oulu and Helsinki, Finland. The National Institute for Health and Welfare (THL) covered the data linkages and the work of Mika Gissler. There are no competing interests to be reported.

Health care costs resulting from IVF: prenatal and neonatal periods

BACKGROUND

The use of expensive infertility treatments is increasing rapidly. To compare the prenatal and neonatal health care costs after IVF and spontaneous conception, we conducted a study based on a cohort of IVF and control pregnancies and neonates.

METHODS

A cohort of 215 IVF mothers and 255 IVF neonates were compared with a cohort of 662 control mothers and 388 control children, randomly chosen from the Finnish Medical Birth Register and matched for sex, year of birth, area of residence, parity, maternal age, socioeconomic status and plurality. The analyses on prenatal and neonatal costs were performed by plurality. Singletons were also compared with twins. The cost calculations were based on the known level of utilization of maternal and neonatal health care services.

RESULTS

The total health care costs for an IVF singleton until the end of the neonatal period were 5780 and 15 580 for an IVF twin. The health care costs were 1.3-fold for IVF singletons and 1.1-fold for IVF twins compared to control singletons and twins. The costs for twins were approximately 3-fold compared to singletons.

CONCLUSIONS

The health care costs of an IVF singleton neonate were higher than those of a spontaneously conceived control neonate with similar backgrounds. For twins the health care costs were equal. Multiple births increase the health care costs and therefore the reduction of multiple pregnancies is the most effective way to reduce the health care costs resulting from IVF.

Growth, psychomotor development and morbidity up to 3 years of age in children born after IVF

BACKGROUND

To examine the long-term child outcome after IVF until the age of 3 years in Northern Finland, we conducted a population-based cohort study.

METHODS

First, a cohort of 299 IVF children born in 1990-1995 was compared with a cohort of 558 controls representing the general population in terms of a multiple birth rate of 1.2%, randomly chosen from the Finnish Medical Birth Register (FMBR) and matched for sex, year of birth, area of residence, parity, maternal age and social class (full sample analyses). Second, IVF singletons (n = 150) were compared with singleton controls (n = 280). Third, a plurality matched control cohort (n = 100) for IVF twins (n = 100) was randomly chosen, matched as above, from the FMBR and analysed separately. Infant mortality rate was compared with the national rate from the FMBR.

RESULTS

Infant mortality in the IVF group was >2-fold higher compared to the national rate in the general population. The risk (OR, 95% CI) of low weight and height, below the lowest quartile, at 1 year of age (1.6, 1.1-2.2; 1.6, 1.1-2.4) and 2 years of age (1.5, 1.1-2.4; 1.7, 1.2-2.5) was significantly higher in the IVF group when compared with the general population control group. No statistically significant differences were found in the psychomotor development between the cohorts. Cumulative incidence of different diseases up to 3 years of age was significantly higher among IVF children in the full sample and singleton analyses (OR, 95% CI: 2.3, 1.7-3.2; 2.1, 1.3-3.3 respectively) especially regarding respiratory diseases (3.5, 1.9-6.5; 3.1, 1.0-9.4) and diarrhoea (3.7, 2.2-6.2; 5.7, 2.6-12.7), but not in twin comparisons.

CONCLUSIONS

The growth of IVF children was behind that of control children during the first 3 years of life, but their psychomotor development was similar. Their postnatal health was worse, probably reflecting the problems in the neonatal period.