Calculation of offspring in Astrology is very common ,simple but an important factor.Generally 5th Houses of the Horoscope, Planets located in 5th House, location of the 5th House Lord, 5th House aspected by malefic or beneficial planets etc are considered for progeny calculation.More over the Planets Jupiter and Venus play a role in conception.If Jupiter or 5th House badly connected by Mars or 8th House Lord,abortion may happened during Pregnancy.Tentative prediction for male or female child birth may possible in Astrology but in such cases both the Horoscope of Husband and Wife need to be judged critically.