Charak Samhita
मैथुनादतिबालायाः पृष्ठकट्यूरुवङ्क्षणम् । रुजन् दूषयते योनिं वायुः प्राक्चरणा हि सा ॥२०॥
॥ Prakcharana yonivyapat॥ When the sexual intercourse is performed in too premature (younger/adolescent) girls, then vata gets aggravated leading to vitiation of the genital tract and produces pain in back, waist, thighs and groins. This is known as Prakcharana.
english translation
maithunAdatibAlAyAH pRSThakaTyUruvaGkSaNam । rujan dUSayate yoniM vAyuH prAkcaraNA hi sA ॥20॥
hk transliteration by Sanscript