Washington, Aug 3 - A foetus may not survive if the mass of placenta which supplies food and oxygen to the developing baby is small, says a new study.

Limits in current technology prevent monitoring the growth of the placenta, which, like the petrol tank of a car, fuels the foetus.

Foetal death, or intra-uterine foetal demise (IUFD), affects 30,000 women every year in the US alone. Until now, there has been no easy way to determine how much 'petrol' is left in the placenta's tank.

Harvey J. Kliman, study co-author and scientist at the Yale School of Medicine (YSM), decided to study this issue after noting that many late-term pregnancy losses were associated with very small mass of placentas.

He theorised that in much the same way that an obstetrician uses ultra-sounds to follow the growth of the foetus, or a paediatrician weighs and measures children to ensure they are growing normally, the growth of the foetus' placenta could be monitored.

When Kliman asked perinatologists (maternal foetal medicine specialists) why they did not look at the placenta when performing routine ultra-sounds, the answer was always the same.