Fetal Environment Is a Major Determinant of the Neonatal Blood Thyroxine Level: Results of a Large Dutch Twin Study.

CONTEXT: The interindividual variability in thyroid hormone function parameters is much larger than the intraindividual variability, suggesting an individual set point for these parameters. There is evidence to suggest that environmental factors are more important than genetic factors in the determination of this individual set point. OBJECTIVE: This study aimed to quantify the effect of genetic factors and (fetal) environment on the early postnatal blood T4 concentration. METHODS: This was a classical twin study comparing the resemblance of neonatal screening blood T4 concentrations in 1264 mono- and 2566 dizygotic twin pairs retrieved from the population-based Netherlands Twin Register. Maximum-likelihood estimates of variance explained by genetic and environmental influences were obtained by structural equation modeling in data from full-term and preterm twin pairs. RESULTS: In full-term infants, genetic factors explained 40%/31% of the variance in standardized T4 scores in boys/girls, and shared environment, 27%/22%. The remaining variance of 33%/47% was due to environmental factors not shared by twins. For preterm infants, genetic factors explained 34%/0% of the variance in boys/girls, shared environment 31%/57%, and unique environment 35%/43%. In very preterm twins, no significant contribution of genetic factors was observed. CONCLUSION: Environment explains a large proportion of the resemblance of the postnatal blood T4 concentration in twin pairs. Because we analyzed neonatal screening results, the fetal environment is the most likely candidate for these environmental influences. Genetic influences on the T4 set point diminished with declining gestational age, especially in girls. This may be due to major environmental influences such as immaturity and nonthyroidal illness in very preterm infants.

Delayed start of diphtheria, tetanus, acellular pertussis and inactivated polio vaccination in preterm and low birth weight infants in the Netherlands.

BACKGROUND: It is recommended that preterm (PT) and low birth weight infants be vaccinated according to standard guidelines. We studied the timeliness of the first diphtheria, tetanus, acellular pertussis and inactivated polio vaccination in the Netherlands, by gestational age (GA) and birth weight (BW). METHODS: We included all vaccinated children born during 2006-2010. Data from the national immunization register were used to determine the vaccination age and the proportion of timely vaccinated infants (<70 days). Results were compared between groups based on GA (extreme PT: <32, PT: 32-36, full term (FT): ≥37 weeks) and BW. Characteristics associated with the timeliness of vaccination were studied by Cox regression analyses. RESULTS: The median vaccination age was lower with a higher GA/BW. The proportion of timely vaccinated infants was 66% for extreme PT, 76% for PT and 82% for FT infants. Similar results were seen by BW. Overall, the proportion of timely vaccinated infants increased from 2006 (77%) until 2010 (85%) and there were regional differences and differences by ethnicity. In extreme PT and PT infants, living in a very highly urbanized municipality and being light for GA were associated with less timely vaccination. Being vaccinated in a hospital was associated with a timelier vaccination in extreme PT infants. However, the reverse was seen for PT infants. CONCLUSIONS: In the Netherlands, PT and low birth weight infants were less often timely vaccinated than FT infants and were, therefore, at increased risk of vaccine-preventable infections. In FT infants, the timeliness of vaccination is better but could also be optimized.

Antenatal screening for HIV, hepatitis B and syphilis in the Netherlands is effective.

BACKGROUND: A screening programme for pregnant women has been in place since the 1950s in the Netherlands. In 2004 universal HIV screening according to opting out was implemented. Here, we describe the evaluation of the effectiveness of antenatal screening in the Netherlands for 2006-2008 for HIV, hepatitis B virus (HBV) and syphilis in preventing mother-to-child transmission, by using various data sources. METHODS: The results of antenatal screening (2006-2008) were compared with data from pregnant women and newborns from other data sources. RESULTS: Each year, around 185,000 pregnant women were screened for HIV, HBV and syphilis. Refusal rates for the screening tests were low, and were highest (0.2%) for HIV. The estimated annual prevalence of HIV among pregnant women was 0.05%.Prior to the introduction of screening, 5-10 children were born with HIV annually After the introduction of screening in 2004, only 4 children were born with HIV (an average of 1 per year). Two of these mothers had become pregnant prior to 2004; the third mother was HIV negative at screening and probably became infected after screening; the fourth mother's background was unknown. Congenital syphilis was diagnosed in fewer than 5 newborns annually and 5 children were infected with HBV. In 3 of these, the mothers were HBeAg positive (a marker for high infectivity). We estimated that 5-10 HIV, 50-75 HBV and 10 syphilis cases in newborns had been prevented annually as a result of screening. CONCLUSIONS: The screening programme was effective in detecting HIV, HBV and syphilis in pregnant women and in preventing transmission to the child. Since the introduction of the HIV screening the number of children born with HIV has fallen dramatically. PREVIOUS PUBLICATION: [Translation from: 'Prenatale screening op hiv, hepatitis B en syphilis in Nederland effectief', published in 'The Dutch Journal of Medicine ' (NTVG, in Dutch)].

[Antenatal screening in the Netherlands for HIV, hepatitis B and syphilis is effective]. / Prenatale screening op hiv, hepatitis B en syfilis in Nederland effectief.

OBJECTIVE: Evaluation of the effectiveness of antenatal screening in the Netherlands for HIV, hepatitis B virus (HBV) and syphilis, in preventing mother-to-child transmission. DESIGN: Descriptive. METHODS: The results of antenatal screening in the period 2006-2008 were compared with data from pregnant women and newborns from other data sources. RESULTS: Each year, around 185,000 pregnant women were screened for HIV, HBV and syphilis. Refusal rates for the screening tests were low, and were highest (0.2%) for HIV. Prior to the introduction of screening, 5-10 children were born with HIV annually. After the introduction of screening in 2004, only 4 children were born with HIV (an average of 1 per year). Two of these mothers had become pregnant prior to 2004; the third mother was HIV negative at screening and probably became infected after screening; the fourth mother's background was unknown. Congenital syphilis was diagnosed in fewer than 5 newborns annually and 5 children were infected with HBV. In 3 of these the mothers were HBeAg positive (a marker for high infectivity). We estimated that 5-10 HIV, 50-75 HBV and 10 syphilis cases in newborns had been prevented annually as a result of screening. CONCLUSION: The screening programme was effective in detecting HIV, HBV and syphilis in pregnant women and in preventing transmission to the child. Since the introduction of the HIV screening the number of children born with HIV has fallen dramatically.

Parental attitude towards childhood HBV vaccination in The Netherlands.

In The Netherlands, children with at least one parent born in a hepatitis B virus (HBV) endemic country are offered HBV vaccination within the National Immunization Programme (NIP) since 2003. However, in the eligible group the HBV vaccine coverage is lower than the DPT-IPV-Hib coverage. We therefore conducted a questionnaire survey in order to determine the acceptance of HBV vaccination among parents of eligible children. Given the possibility that universal HBV vaccination will be introduced in the Netherlands, we also assessed the attitude towards universal HBV vaccination among parents whose children are currently not eligible for HBV vaccination. Participants were selected based on the registered vaccination status of their child. Only 13 of 83 parents (16%) within the HBV-eligible group whose child was registered as 'incompletely vaccinated' for HBV reported that they refused a vaccine for their child. Risk factors for HBV refusal were a low risk perception of HBV, a high socioeconomic status and one parent born in The Netherlands. Within the non-eligible group, we found that 9% (95% CI: 3-22%) of the parents whose child was fully vaccinated with DPT-IPV-Hib had a negative attitude towards universal HBV vaccination. Considering the recent recommendation of the Dutch Health Council to introduce universal HBV vaccination, this resistance deserves further attention.

[High vaccination coverage of the National Immunization Programme in the Netherlands]. / Hoge vaccinatiegraad van het Rijksvaccinatieprogramma in Nederland.

OBJECTIVE: To describe vaccination coverage of the National Immunization Programme (NIP) in the Netherlands for the years 2006-2008. DESIGN: Descriptive, retrospective. METHOD: Vaccination coverage was determined per vaccination and birth cohort based on data from the vaccination-registration system 'Praeventis'. This new system enables more accurate testing for compatibility with NIP guidelines. Furthermore, it was determined on an individual level whether the desired vaccination status was reached before a certain target age (1, 2, 5 or 10 years). RESULTS: In the final year reported, all national vaccination percentages came up to the WHO standards. Vaccination coverage for babies ranged from 94.5% for diphtheria, whooping cough, tetanus and polio (DTaP-IPV) to 96.0% for measles, mumps and rubella (MMR). The coverage for toddlers and school-aged children was over 90% for each of the vaccinations. In 5 of the 12 Dutch provinces and 128 of the 443 municipalities, one or more vaccination percentages were below the standard of 90%. Vaccination coverage for the second MMR vaccination and for hepatitis B vaccination in children of whom one or both parents were born in a country where the incidence of hepatitis B is higher than average, was relatively low (92.5% and 90.7%, respectively). CONCLUSION: Vaccination coverage in the Netherlands is high. In general, vaccination coverage for toddlers and school-aged children requires extra attention. This applies in particular to the second MMR vaccination and to vaccination in children of whom one or both parents were born in a country where the incidence of hepatitis B is higher than average.