Antithyroid antibodies underlying thyroid abnormalities and miscarriage or pregnancy induced hypertension

Sir, I read with interest R. Lamont’s commentary (October 1993) on P-agonists. He makes several very good points, primarily that the perinatal morbidity and mortality are too great a problem to justify the therapeutic nihilism some authors adopt. The nature of preterm birth is such that many patients are not candidates for tocolysis, but this should not blind us to the benefits which he mentions in his article. In addition, there are real benefits in identifying those patients most likely to benefit from tocolysis, as continuing a pregnancy in many instances is in the interest of neither the fetus nor the mother, particularly when preterm labour is the cause of intrauterine infection. I would suggest that clinical criteria are neither sensitive nor specific, and increased use be made of diagnostic amniocentesis. I agree with his assertion that P-agonists be used with caution, but the fact remains that major maternal morbidity, and even mortality, is still occurring with the use of P-agonists, even after 20 years of clinical practice, which suggests that the drug has a low therapeutic index. Although we do not have the perfect tocolytic, and never will, there is another more potent and safer tocolytic which also has been available for nearly 20 years, namely indomethacin. Therapy seldom needs to be discontinued due to maternal side effects, as is the case with 6-agonists (Kierse 1992). The main concern relates to ductal constriction, and resultant pulmonary hypertension with persistent fetal circulation. This effect is, however, reversible on cessation of therapy and gestationally dependent, even when doses significantly in excess of those usually employed for tocolysis are used (Eronen 1991). Even if there was occasional serious fetal morbidity associated with indomethacin use, this could easily be offset by the high maternal tolerance and increased efficacy over currently available drugs. Although there are few trials which directly compare P-agonists and indomethacin, meta-analysis of those trials available for comparison shows a decrease in low birthweight infants and a strong tendency towards a decrease in perinatal mortality with relatively few numbers and considerably less than those required by P-agonists (Kierse 1992).