Aims

To explore what the discrepancies between date of birth and expected date of birth have on neuro-cognitive outcomes in preterm infants.

Hypotheses

It is well recognised that infants born preterm, both at extreme gestations (e.g. less tah 28 weeks) but also at more modest gestations (e.g. 32-36 weeks) have worse outcomes at school age, including cognition and school performance. While direct neurological injury is an important component of this (particularly in the extremely preterm group) the process of prematurity has consequences on the measurement of these age-dependent variables and the school processes that the infants go through.

In most work cognitive and school measures are measured when the infants reach a specified age, and are rarely corrected for any prematurity. In addition infant's born preterm are more likely to enter school a year earlier than if they had been born at term with potential impacts on their ability to perform at this level.

Methodology

We will assess the relative risk, and population impact of being born at different gestational ages compared to term infants. Gestational groups are anticipated to be less than 28 weeks, 28 to 32 weeks, 33 to 36 weeks and 37 to 42 weeks. Post term (greater than 42 week infants) will not be included. Associations of these gestational groups with the presence of special educational needs and cognition will be derived and an estimate of population impact calculated. Unadjusted and adjusted results will be derived consistent with previous work.

This will be done in three ways:

1) Matching each preterm infant with a term infant born in the same month and year.

2) Matching each preterm infant with a term infant with equivalent expected date of birth (month and year)

3) Matching each preterm infant with a term infant with equivalent expected date of birth (month and year) who also entered school in the same school year.

Exposure: Gestation

Outcomes: Special Educational Needs and Cognition

Confounders: Birth condition, growth, gender, parity, maternal hypertension, maternal pyrexia, mode of delivery, maternal age, socio-economic position, educational achievement, tenure, crowding index, ethnicity, place of birth