MATURATION OF THE HYPOTHALAMO-PITUITARYGONADAL AXIS IN PRETERM GIRLS

Abstract

We found oestradiol producing ovarian cysts and high serum concentrations of oestradiol in four very pre-term infants at a postconceptional age that slightly preceded the expected time of delivery.To determine the maturation of the hypothalamo-pituitary-gonadal axis in these infants measurements of serum concentration of luteinizing hormone (LH) and follicle stimulating hormone (FSH) were made before and after an i.v. injection of luteinizing hormone releasing hormone (LHRH). At the time when the girls developed cysts, they had a postpubertal type of response to LHRH, i.e. the increase in LH was more marked than the increase in FSH. Some months later they had a prepubertal type of response and a low preinjection serum concentration of LH as expected at that age.We then made a series of LHRH tests in all consecutive preterm girls born at a gestational age of less than 30 weeks at a postconceptional age of 32-33 weeks. All these girls had a postpubertal type of response to an LHRH injection, and the preinjection concentrations of LH and FSH were very high. When the tests were repeated at a date later than the calculated time of birth they all had a prepubertal type of response with low basal concentrations of FSH and LH. The oestradiol concentration was low on both occasions. Two girls developed very small ovarian cysts. The strong stimulation of the ovaries after birth may be a consequence of withdrawal of placental steroids.The feed-back system may be too immature in preterm girls to respond to low levels of oestradiol, resulting in high levels of gonadotrophins and an “ovarian hyperstimulation syndrome”.