title: Levothyroxine dose adjustment in hypothyroid women achieving pregnancy through IVF.
abstract: OBJECTIVE
  About one out of two women with primary hypothyroidism has to increase the dosage of exogenous levothyroxine (L-T4) during pregnancy. Considering the detrimental impact of IVF on thyroid function, it has been claimed but not demonstrated that L-T4 dose adjustment may be more significant in hypothyroid women who become pregnant after IVF.
  
  
  METHODS
  Retrospective cohort study.
  
  
  METHODS
  Hypothyroid-treated women who achieved a live birth through IVF were reviewed. Women could be included if thyroid function was well compensated with L-T4 before the IVF cycle (i.e., serum TSH <2.5  mIU/l and serum free T4 within the normal range). Serum TSH and dose adjustment were evaluated at five time points during pregnancy. The trimester ranges for serum TSH considered as reference to adjust L-T4 therapy were 0.1-2.5  mIU/l for the first trimester, 0.2-3.0  mIU/l for the second trimester, and 0.3-3.0  mIU/l for the third trimester.
  
  
  RESULTS
  Thirty-eight women were selected. During the whole pregnancy 32 women (84%; 95% CI: 72-96%) required an increase in the dose of L-T4. In most cases (n=28), this occured within the first 5-7 weeks of gestation (74%, 95% CI: 58-85%). At 5-7 weeks of gestation, the median (interquartile range) increase of L-T4 dose for the whole cohort was 26% (0-50%). At 30-32 weeks, it was 33% (14-68%). In order to identify predictive factors of dose adjustment, we compared women who did (n=28) and did not (n=10) adjust L-T4 dosage at 5-7 weeks' gestation. Significant differences emerged for thyroid autoimmunity prevalence and for the distribution of hypothyroidism aetiology.
  
  
  CONCLUSIONS
  The vast majority of hypothyroid-treated women who achieve pregnancy through IVF need an increase in the L-T4 dose during gestation. This requirement tends to occur very early during gestation.
authors.affiliation: Infertility UnitFondazione Ca' Granda, Ospedale Maggiore Policlinico, Via M. Fanti, 6, 20122 Milan, ItalyUniversità degli StudiMilan, Italy Infertility UnitFondazione Ca' Granda, Ospedale Maggiore Policlinico, Via M. Fanti, 6, 20122 Milan, ItalyUniversità degli StudiMilan, Italy andreabusnelli@live.it.
authors.forename: Andrea
authors.initials: A
authors.lastname: Busnelli
authors.affiliation: Infertility UnitFondazione Ca' Granda, Ospedale Maggiore Policlinico, Via M. Fanti, 6, 20122 Milan, ItalyUniversità degli StudiMilan, Italy.
authors.forename: Guia
authors.initials: G
authors.lastname: Vannucchi
authors.affiliation: Infertility UnitFondazione Ca' Granda, Ospedale Maggiore Policlinico, Via M. Fanti, 6, 20122 Milan, ItalyUniversità degli StudiMilan, Italy.
authors.forename: Alessio
authors.initials: A
authors.lastname: Paffoni
authors.affiliation: Infertility UnitFondazione Ca' Granda, Ospedale Maggiore Policlinico, Via M. Fanti, 6, 20122 Milan, ItalyUniversità degli StudiMilan, Italy Infertility UnitFondazione Ca' Granda, Ospedale Maggiore Policlinico, Via M. Fanti, 6, 20122 Milan, ItalyUniversità degli StudiMilan, Italy.
authors.forename: Sonia
authors.initials: S
authors.lastname: Faulisi
authors.affiliation: Infertility UnitFondazione Ca' Granda, Ospedale Maggiore Policlinico, Via M. Fanti, 6, 20122 Milan, ItalyUniversità degli StudiMilan, Italy Infertility UnitFondazione Ca' Granda, Ospedale Maggiore Policlinico, Via M. Fanti, 6, 20122 Milan, ItalyUniversità degli StudiMilan, Italy.
authors.forename: Laura
authors.initials: L
authors.lastname: Fugazzola
authors.affiliation: Infertility UnitFondazione Ca' Granda, Ospedale Maggiore Policlinico, Via M. Fanti, 6, 20122 Milan, ItalyUniversità degli StudiMilan, Italy Infertility UnitFondazione Ca' Granda, Ospedale Maggiore Policlinico, Via M. Fanti, 6, 20122 Milan, ItalyUniversità degli StudiMilan, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Fedele
authors.affiliation: Infertility UnitFondazione Ca' Granda, Ospedale Maggiore Policlinico, Via M. Fanti, 6, 20122 Milan, ItalyUniversità degli StudiMilan, Italy.
authors.forename: Edgardo
authors.initials: E
authors.lastname: Somigliana
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D005307:Fertilization in Vitro; D020249:Hormone Replacement Therapy / Q000379:methods*; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000188:drug therapy*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood / Q000188:drug therapy*; D011264:Pregnancy Trimesters / Q000097:blood; D012189:Retrospective Studies; D020554:Sperm Injections, Intracytoplasmic; D013960:Thyroid Function Tests; D013974:Thyroxine / Q000008:administration & dosage*
chemical_list: D013974:Thyroxine