<prompt> If rubella occurs in 9-10 weeks of pregnancy what is the chance of transmission to the fetus -85203040  <response>: first trimester is most disastrous for foetus as the organs are developing infection during this period results in abnormalities in infants in 85 in second trimester,detectable defects are found in 16of infants after 20 weeks,bih defects are uncommon park,edition 23,page 151 