Charak Samhita
चतुर्थे मासि स्थिरत्वमापद्यते गर्भः, तस्मात्तदा गर्भिणी गुरुगात्रत्वमधिकमापद्यते विशेषेण ॥२०॥
॥ Features in fourth month॥ During fourth month of gestation, the fetus attains stability due to which, the pregnant woman feels more heaviness in her body.
english translation
caturthe mAsi sthiratvamApadyate garbhaH, tasmAttadA garbhiNI gurugAtratvamadhikamApadyate vizeSeNa ॥20॥
hk transliteration by Sanscript