New charts for ultrasound dating of pregnancy planet personnel dating

new charts for ultrasound dating of pregnancy-52

One study found brain hemorrhages in mouse pups exposed in the womb to pulsed ultrasound at doses similar to those used on human babies.

Another study found exposing adult mice to dosages typical of obstetric ultrasound caused a 22 percent reduction in rate of cell division and a doubling of the rate of apoptosis of cells in small intestine.

significant temperature increase in tissue or visible motion of particles due to radiation pressure streaming effects.

The risk of inducing thermal effects is greater in the second and third trimesters, when fetal bone is intercepted by the ultrasound beam and significant temperature increase can occur in the fetal brain.(1) thermal rather than nonthermal mechanisms are more likely to induce adverse effects in utero, and (2) while the probability of an adverse thermal event is usually small, under some conditions it can be disturbingly high.

A recent study suggests that heating in late-pregnancy fetal tissues exposed to normal pulsed and continuous Doppler ultrasound may be higher than what is regarded as safe: 2.5 to 10.4 degrees F (1.4 – 5.8 C) respectively.

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