Increased subepithelial reticular membrane thickness is an early feature of airway remodelling in preschool wheeze18 and childhood asthma,19 we therefore analysed mRNA levels of genes associated with remodelling including FIZZ1,20 fibronectin,21 vimentin,22 MMP-2,23 amphiregulin24 and collagen-1α1,25 from neonatal mice exposed to paracetamol during pregnancy alone (figure 1A), or lactation alone (figure 1D). This evidence concerns the gene MMP2 and asthma.