Lactation m the presence of adequate nursing IS known to be
associated with a protracted period of natural infertility. This effect IS of
major demographic Importance in our country in order to reduce the
rapidly expanding population and consequently its impact on the
national income.
The present study was performed to clarify endocrinal changes
associated with prolonged lactation for one and a half year and to
compare such hormonal melieu with that of corresponding groups
laclating for 6 months or one year.
One hundred and two lactating females were investigated. All were
of age group ( 20- 35y ), parity ( 1 to 5 ), and of nearly similar
socioeconomic status. They were classified into three groups according
to the duration of lactation, whether it was 6 months, 12 months or 18
months. Each group was subclassified into amenorrhoeic and
menstruating according to the return of meunstruation. From each
participant two venous blood samples were collected, each of which is
10 mJ. The sera separated were examined by radioimmunoassay
techniques for estimation of follicle-stimulating hormone (FSH),
luteinizing hormone (LH), prolactin (PRLI and progesterone according to
WHO-RIA Matched Program.
Rnalysis of the results of hormonal assays reuealed the
following Items:
1- No appreciable changes were noted in serum prolactin with
the advance of time among lactating amenorrhoeic females. However, a
gradual decline occurred in menstruating ones being marked at the end
of the first year of lactation. Comparison of mean prolactin levels in
amenorrhoeic in relation to menstruating nursing females shows a
higher degree of hyperprolactinemia at any interval of estimation.
2-- FSH estimation indicated no changes throughout maintained
lactation regardless of return of menstruation.
3-- As a function of advance in time after delivery, there was a
gradual increase in mean serum LH levels both in amenorrhoeic and
menstruating nursing females. Such increase was only remarkable by
the onset of the second year of lactation.
4-- Mean FSH and LH levels were corresponding to levels seen in
the normal follicular phase of the cycle.
5·· Insignificant changes in serum progesterone level were noted at
various intervals of estimation, both in amenorrhoeic and menstruating
lactating females.
6- The return of menstruation during lactation appeared to be
associated only with declining PRL and rising progesterone levels
particularly at the end of the first year.
7 - Evaluation of corpus luteum activity revealed anovulation in
amenorrhoeic females throughout lactation except at 18 months where
22.22 of cases experienced corpus luteum insufficiency. In
menstruating mothers. the percente of females showing anovulation
declined by time. The resumed ovarian function was largely inadequate
with only few cases of normal ovulation at 12 months interval.
CONCLUSION
Prolonged lactation is associated with hyperprolactinemia,
hypogonadotropinemia and ovarian quiescence. Such lactational
hyperprolactinemia may have a suppressive effect on gonadotropin
secretion. This may be apparent from the significant positive correlation
between declining prolactin level by the end of the first year and rising
LH secretion during the second year of lactation. Moreover,
hyperprolactinemia may have a suppressive effect on ovarian
steriodogenesis. This could be deduced from the starting improvement
In corpus luteum function in menstruating nursing females with the
declining PRLlevel.
Maintainance of lactation amenorrhoea appears to be relevant to
the degree of hyperprolactinemia as a declining PRLlevel is the number
one of the clinical determinants of the return of menstruation.
Moreover, it is obvious that while lactational amenorrhoea is associated
with complete gonadal suppression, resumption of menstruation during
prolonged lactation does not perclude return of ovulation. Cycles during
lactation are associated with increasing incidence of poor luteal phases.
Consequently, maintained breast-feeds through maintainance of
lactational hyperprolactinemia is essential for prolongation of lactational
amenorhoea and infertility, thus maximizing the contraceptive effect of
breast feeding. It will. therefore, be of an optimum value to direct our
6-
attention towards full breast feeding c2mpains in attempt to decrease
the rapid expansion of population, particularly after other means of
contraception appeared to be either irsufficient or entailing diverse
adverse effects. |
