Thyroid disease and other endocrine disorders in pregnancy

Optimal usage of the GnRH antagonists: a review of the literature

Gonadotropin-releasing hormone (GnRH) antagonists, which became commercially available from 1999, have been used for the prevention of premature luteinizing hormone (LH) surges in controlled ovarian stimulation for in vitro fertilization or intracytoplasmic sperm injection. This review focuses on the recent literature on the use of GnRH antagonists and provides guidelines for optimal use in light of increasing evidence showing that GnRH antagonists are safe and effective, allowing flexibility of treatment in a wide range of patient populations. This includes patients undergoing first-line controlled ovarian stimulation, poor responders, and women diagnosed with polycystic ovary syndrome. The GnRH antagonist offers a viable alternative to the long agonists, providing a shorter duration of treatment with fewer injections and with no adverse effects on assisted reproductive technology outcome. This results in a significantly lower amount of gonadotropins required, which is likely to lead to improved patient compliance.

Follicular growth and oocyte maturation in GnRH agonist and antagonist protocols for in vitro fertilisation and embryo transfer

BACKGROUND

The aim of this study was to evaluate the response to treatment in a group of patients undergoing IVF and randomised to receive GnRH-antagonist or the GnRH-agonist. The endpoints were the pattern of follicular growth, the maturity of the oocytes collected, the embryo quality and the pregnancy outcome.

METHODS

A total of 136 patients undergoing IVF were included. Sixty-seven patients were allocated to the GnRH antagonist and 69 patients to the GnRH agonist. GnRH antagonist was administered when the leading follicle reached a diameter of 12-14 mm. GnRH agonist was administered in a long luteal protocol.

RESULTS

The mean numbers of oocytes retrieved and mature oocytes were significantly higher in the agonist than in the antagonist group (p < 0.02 and p < 0.01, respectively). Embryo quality, implantation rate, clinical pregnancy rates, ongoing pregnancy rate and miscarriage rate were similar in both groups.

CONCLUSIONS

Better follicular growth and oocyte maturation are achieved with GnRH agonist treatment. However, both regimens seem to have similar efficacy in terms of implantation and pregnancy rates. Further studies clarifying the effect of the GnRH antagonist on ovarian function are needed, as well as a clear definition of the best period of the follicular phase for the GnRH antagonist administration.

Comparison of GnRH agonists and antagonists in normoresponder IVF/ICSI in Turkish female patients

PURPOSE

To evaluate the results of gonadotropin-releasing hormone agonist (GnRHa) and gonadotropin-releasing hormone antagonist (GnRHant) use in two demographically matched groups of normoresponder in-vitro fertilisation or intracytoplasmic sperm injection (IVF/ICSI) patients in a prospective study.

METHODS

We randomised 93 patients undergoing IVF/ICSI between May 2005 and August 2006. Patients with IVF indications were included except for those with polycystic ovary syndrome or azoospermia, women older than 38 years and those with follicle-stimulating hormone (FSH) > or =10 IU/ml. Patients were stimulated with standard 225 IU recombinant FSH. In Group I (n=45) a daily dose of GnRHant cetrorelix acetate 0.25 mg was administered when follicles reached a diameter of > or =14 mm. Group II (n=48) patients were desensitised with the GnRHa, leuprolide acetate, in a long protocol. Human chorionic gonadotropin (hCG) was administered when at least three follicles of 18 mm in diameter were observed. Oocyte retrieval was scheduled 36 hours following hCG administration and embryos were transferred on day 3 after oocyte retrieval.

RESULTS

The two groups were homogenous for age, infertility duration, basal FSH and serum oestradiol (E2) (P=0.537, P=0.911, P=0.103 and P=0.733, respectively). In Group II (the GnRHa group) more antral follicles (P<0.001), a longer induction duration (P=0.017) and higher peak E2 levels (P<0.001) were observed. No differences were observed in the number of oocytes retrieved (P=0.749), embryos achieved and transferred (P=0.677), or fertilisation rates (P=0.839) between the two groups. There was no statistically significant difference between groups in clinical pregnancy rates, cycle cancellation and ovarian hyperstimulation (P=0.437, P=0.109 and P=0.415, respectively).

CONCLUSION

GnRHant and GnRHa provide comparable results in normoresponder patients, while GnRHant allows a greater flexibility in their treatment.

Among patients treated for IVF with gonadotrophins and GnRH analogues, is the probability of live birth dependent on the type of analogue used? A systematic review and meta-analysis

This systematic review and meta-analysis aimed to answer the following clinical question: among patients treated for IVF with gonadotrophins and GnRH analogues, is the probability of live birth per randomized patient dependent on the type of analogue used? Eligible studies were randomized controlled trials (RCTs), published as a full manuscript in a peer-reviewed journal, that contained sufficient information to allow ascertainment of whether randomization was true and whether equality was present between the groups compared. A literature search identified 22 RCTs comparing GnRH antagonists and GnRH agonists that involved 3176 subjects. Where live birth was not reported in a study that fulfilled the inclusion criteria, an effort was made to contact the corresponding authors to retrieve the missing information. If this was not possible, the reported outcome measure, clinical pregnancy or ongoing pregnancy was converted to live birth in 12 studies using published data (Arce et al., 2005). No significant difference was present in the probability of live birth between the two GnRH analogues [odds ratio (OR), 0.86; 95% confidence intervals (CI), 0.72 to 1.02]. This result remains stable in subgroup analysis that ordered the studies by type of population studied, gonadotrophin type used for stimulation, type of agonist protocol used, type of agonist used, type of antagonist protocol used, type of antagonist used, presence of allocation concealment, presence of co-intervention and the way the information on live birth was retrieved. In conclusion, the probability of live birth after ovarian stimulation for IVF does not depend on the type of analogue used for pituitary suppression.

Pharmacokinetics and Pharmacotherapy of Thionamides in Pregnancy

Hyperthyroidism occurs in approximately 1 in every 1000 to 2000 pregnancies. Although the signs and symptoms of the disease are similar in the pregnant and nonpregnant patient, the complications of hyperthyroidism can have even more profound consequences for the mother and fetus during gestation. These include maternal heart failure, preeclampsia, miscarriage, and preterm labor; as well as fetal loss and low birth weight. Furthermore, thyroid function and laboratory testing for hyperthyroidism are altered in pregnancy. The gestational increase in thyroid size, increased thyroid-binding globulin levels, increased serum total T4 and total T3 levels, and decreased thyroid stimulating hormone levels often confuses the evaluation of the thyroid status in pregnancy. Worldwide, the thionamides-propylthiouracil, methimazole, and carbimazole-have been used in pregnancy for the treatment of hyperthyroidism. However, propylthiouracil has been the drug of choice in the United States because it is believed to have less potential to induce fetal/neonatal hypothyrodism, to cross the placenta and into breast milk to a lesser degree, and to be less teratogenic than methimazole or carbimazole. None of the above have been substantiated in more recent studies. The pharmacokinetics of the thionamides in the pregnant and nonpregnant states, as well as the pharmacotherapeutic recommendation for hyperthyroidism will be reviewed.

Correlation of thyroid stimulating hormone (TSH) level with pregnancy outcome in women undergoing in vitro fertilization

OBJECTIVE

The aim of this study was to determine if pregnancy outcome for women undergoing in vitro fertilization is correlated with pre-conception thyroid-stimulating hormone level.

STUDY DESIGN

We performed a retrospective cohort study of in vitro fertilization cycles in our private practice with an initial positive serum human chorionic gonadotropin level and thyroid-stimulating hormone level available (n = 364). We examined whether or not birth outcome differed between cycles in which the thyroid-stimulating hormone was > 2.5 mIU/L compared with cycles with a thyroid-stimulating hormone level of < or = 2.5 mIU/L. Logistic regression was used to determine the association between thyroid-stimulating hormone level and spontaneous abortion rate.

RESULTS

Delivery outcome was available for 195 cycles, 36% of which had a thyroid-stimulating hormone level > 2.5. The gestational age at delivery was higher in cycles with a thyroid-stimulating hormone < or = 2.5 than for cycles with a thyroid-stimulating hormone > 2.5 (38.5 vs 38.0 weeks for singletons, 36.0 vs 34.6 weeks for twins, overall P = .012 for thyroid-stimulating hormone level). The mean birth weight for cycles with a thyroid-stimulating hormone < or = 2.5 was higher than for cycles with a thyroid-stimulating hormone > 2.5 (7.33 vs 6.78 lbs for singletons, P = .024 and 5.36 vs 4.83 lbs for twins, P = .023). Restricting analysis to cycles where the woman was not taking thyroid replacement did not change the overall conclusions. There was a trend toward increasing risk of miscarriage with increasing thyroid-stimulating hormone level in nondonor cycles, controlling for age and day 3 follicle-stimulating hormone level, but this trend did not reach statistical significance.

CONCLUSION

A pre-conception thyroid-stimulating hormone level > 2.5 mIU/L is associated with a lower gestational age at delivery and lower birth weight in women undergoing in vitro fertilization.