Yogas in Classics 
Sarvarth Chintamani , agreat astrological classic  the eleven combinations , seem to have worked best

1. If the fifth house is aspected by benefics and the fifth lord is aspected by benefics, it assures the birth of children.
2. If the fifth house, the fifth lord or Jupiter receive benefic aspects it assures the birth of children.
3. If the lagna lord be strong and be in the fifth house and Jupiter also be strong , it assures the birth of children.
4. If Jupiter as the fifth lord be aspected by strong Lagna lord it assures the birth of children.
5. If Jupiter as the fifth lord be aspected by strong Lagna lord it assures the birth of children.
6. If Jupiter and the fifth lord be in Vaisheshikamsha (in ten benefic divisions in the divisional horoscopes) the birth of the children is assured .
7. If the lagna lord and the fifth lord be together or if they aspect each other or if they have exchanged places , it assures the birth of children.
8. If the Lagna lord and the fifth lord be in a quadrant and the second lord be strong , there will be birth of children.
9. Find out the Navamsha lord of the fifth lord of the birth horoscope . If the planet is in a good condition or well aspected in the birth horoscope , the birth of children is assured.
10. If both the Lagna and the ninth lords be in the seventh house and the second lord be in the Lagna , the birth of children is
11. Find out the navamsha lord of the seventh lord.If that planet is aspected by the Lagna , ninth or the second lord, the birth of children is assured.

Gulika Brihat Parasher Hora Shastra

Chapter25

If Gulika is in the ascendant , the native will be afflicted by diseases , be lustful, sinful, crafty , wicked and very miserable.

If Gulika is in the 2^nd house the native will be unsightly in appearance, miserable, mean , given to vices , shameless and penniless.

If Gulika is in the 3^rd house , the native will be charming in appearance , will head a village, ,be fond of virtuous men, and be honoured by the king.

If the Gulika is in the 4^th house , the native will be sickly , de void of happiness ,sinful and afflicted due to windy and bilious excesses.

If Gulika is in the 5^th , the native will not be praiseworthy , be poor, short-lived . spiteful , mean , be a eunuch , be sudued by his wife and be a heterodox .

If Gulika is in the 6^th , the native will be devoid of enemies , be strong- bodied , splendorous , liked by his wife , enthusiastic ,very friendly and helpful in disposition

If Gulika is in the 7^th , the native will be subdue to his spouse , be sinful , will go to others’ females , be emaciated , devoid of friendship and will live on wife’s (or a female’s) wealth

If Gulika is in the 8^th the native will be troubled by hunger, be miserable , cruel, very much short-tempered, very unkind , poor and bereft of good qualities .

If Gulika is in the 9^th , the native will undergo many ordeals , be emaciated , will perform evil acts, be very unkind , sluggish and be a tale-bearer.

If Gulika is in the 10^th the native will be endowed with sons , be happy , will enjoy many things , be fond of worshipping gods and fire and will practice meditation and religion.

If Gulika is in the 11^th , the native will enjoy women of class, be a leader of men, be helpful to his relatives, be short in stature and  be an emporer.

If Gulika is in  the 12^th , the native will indulge in base deeds , be sinful, defective-limbed, unfortunate, indolent and will join mean people

Chapter 16 9 Should the 5^th house be owned by Saturn or Mercury and be occupied  or aspected by Saturn or Mandi, one will have adopted issues.

16 – 23 SShould Mandi be in the ascendant while the ascendant lord is in fall , grief on account of loss of child at the age of 56 will come to pass.

 Group Researches that can be depended

1) Planets and Children - K. N. Rao

2) Planets and Education - Naval Singh

3) Research on delayed  child birth