Growth trend of small uterine fibroids and human chorionic gonadotropin serum levels in early pregnancy An observational study

Small fibroids seem to grow rapidly in the first weeks of pregnancy, with a nonlinear trend, in relation to the similar growth of human chorionic gonadotropin in the same period.

Andrea Ciavattini, M.D., Giovanni Delli Carpini, M.D., Nicolò Clemente, M.D., Lorenzo Moriconi, M.D., Chiara Gentili, M.D., Jacopo Di Giuseppe, M.D.

Volume 105, Issue 5, Pages 1255-1260


To analyze the growth trend of small uterine fibroids during early pregnancy, evaluating the potential factors involved, with particular interest in hCG levels.

Observational study.

Tertiary care university hospital.

Women who had an ultrasound diagnosis of small myomas (diameter, ≥10 mm and ≤50 mm) from January 2007 to December 2013, and who subsequently became pregnant within 1 year.


Main Outcome Measure(s):
Three additional ultrasound examinations were performed during early pregnancy (7–8, 10–13, and 20–22 complete gestational weeks, respectively) and the modifications in diameter and volume of each uterine fibroid were recorded. A serial evaluation of hCG serum levels from 5–12 weeks was performed.

From the 109 women who fulfilled the study inclusion/exclusion criteria, a significant increase emerged, both for volume and diameter of the detected fibroids. Specifically, a median growth rate (GR) of 122% was observed during the interval of the first to the second ultrasound, whereas a median GR of 108% was detected during the interval between the second and the third ultrasound, and a median GR of 25% between the third and the fourth ultrasound. A significant positive correlation between hCG levels and diameter (R = 0.69) of myomas between 5 and 12 weeks emerged.

A remarkable nonlinear growth of small fibroids during initial pregnancy was observed, with a faster rate in the first trimester and a slow down by midpregnancy. Those changes seem to be related to the similar increase of hCG levels until 12 weeks.

  • Amanda N. Kallen

    Very interesting findings. Do the authors have any speculation as to why smaller fibroids might exhibit more growth? I’m thinking diminished blood flow / diminished exposure to the effects of hCG if your hypothesis re: effects of hCG on fibroid growth is true. It would be interesting to evaluate whether you see even more marked rapid-growth effects in situations where hCG is known to rise even more rapidly (molar pregnancy / twins). Thanks again for an interesting study!

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