High LH in PCO women causes premature activation of oocytes and increases miscarriage rate

 

Why there is RPL (high early miscarriage rate) in PCO?

Ans: In PCO high LH which is present in about 40% of cases. Therefore there is LH induced inhibition of   OMI (oocyte maturation inhibitor) à so in cases of persistent high LH premature maturation of oocyte occurs in cases of PCO who exhibit high LH in midfollicular phase.

.. So , if anovulation is corrected by Letrozole /  CC even then  there may be premature  release of egg   . What happens is this à High LH causes  premature reactivation of meiosis occur with high basal  LH ----So karyotypically abnormal  foetus develops in fair no of cases of PCO --à most of such embryo end in spont Ab. As such we should remember that altered endocrine defects have to be corrected   before induction of ovulation is attempted with. This may be optimizing BMI, Pretreatment with OCP for 3 cycles or Pretreatment with progesterone in previous cycles, In IVF ET planed cycle this optimization of LH is done by Long luteal GnRH agonist 1mg subcut commencing from day 21 of previous cycle .  This is more important to prevent in all early preg miscarriage. In fact LH reports may be raised in PCOS upto 40%. WE are aware of the fact that such gonadotrophins are secreted pulsatile fashion. So better estimate at least twice in a gap of 2 cycles.

 

Oocyte maturation starts in late follicular phase and is a gradual process . Admittedly, many paracrine and growth factors are involved and such are unmodifiabe for us but early persistent rise of LH can be managed by us by anatogonist  cycle or long luteal suppression by agonist  with almost 100% accuracy  . But one should not take it granted that LH  in non downregulated cycles (natural cycle) is fixed  problem, By contrast , there are  variations of hormones from one cycle to another cycle is observed and is some case of LH hyperfuction ovulatory PCO may be observed(escape ovulation ) .

 In foetal life oocytes are arrested at diplotoma stage of first meiotic division and remain dormant as such. Entry of midcycle LH in the follicles inhibits OMI & promotes oocyte maturity. Thus first meiosis is completed 36 hr after ovulation occurs with release of near mature oocyte. There is species specific interval between initiation   of 1 st meiotic division &  fertilization , and embryo cleavage and any stage may go  abnormal.

We know that CC will exert some anti oestrogenic effects in Luteal phase. That may be reason why there is as many as 40% pregnancies achieve by CC ends in spont abortion.