Use of medical imaging techniques in pregnancy dating

In absence of information on the timing of oestrus, it is useful to verify the period of pregnancy in order to decide the birth date or caesarean date. Radiography can be used to confirm pregnancy and facilitate aging of the foetus from 45 days after LH (luteinising hormone) peak. Ultrasonography can establish pregnancy diagnosis from 19 to 21 days after LH peak to term. In addition, the viability of the foetus and stress during parturition can be assessed using this technique. The age of the foetus can be estimated reasonably reliably in the first and second half of pregnancy using foetal and extrafoetal ultrasonography measurements.