भ्रूण के वजन (fetal weight) का अनुमान लगाने के लिए किस सूत्र (formula) का उपयोग किया जाता है?

In a primigravida, engagement of the fetal head typically occurs around:

'Lightening' (descent of the fetal head into the pelvis) in a primigravida typically occurs around which week of pregnancy?

Quickening (the first feeling of fetal movement) is usually felt by a primigravida woman at around how many weeks of gestation?