Pharmacokinetics of vaginal progesterone in pregnancy

Concurrent progestogen and cerclage to reduce preterm birth: a multicenter international retrospective cohort

BACKGROUND

Both progestogens and cerclage are individually effective in preterm birth prevention in high risk pregnancies. However, national and international guidelines cite a lack of data available to comment on the potential benefit of concurrent progestogen therapy after cerclage has been placed. Studies to date have been small with mixed results regarding benefit of concurrent progestogen with cerclage leaving uncertainty regarding best clinical practice.

OBJECTIVE

This study aimed to evaluate whether cerclage with progestogen therapy was superior to cerclage alone in the prevention of spontaneous preterm birth in singleton pregnancies.

METHODS

This is an international retrospective cohort study of singleton pregnancies, without major anomaly or aneuploidy, and with cerclage placed at 10 different institutions in the United States and Colombia from June 2016 to June 2020. Exclusion criteria were lack of documentation regarding whether progestogen was prescribed, unavailable delivery outcome, and pregnancy termination (spontaneous or induced) before 16 weeks' gestation. The exposure of interest was progestogen use with cerclage placement, which included those who continued to use progestogen or who started progestogen after cerclage. The comparison group consisted of those without progestogen use after cerclage placement, which included those who had no progestogen use during the entire pregnancy or who initiated progestogen and then stopped it after cerclage placement. Progestogen type, cerclage indication, maternal baseline characteristics, and maternal/neonatal outcomes were collected. The primary outcome was spontaneous preterm birth at <37 weeks. The secondary outcomes were spontaneous preterm birth at <34 weeks, gestational age at delivery, and a composite neonatal outcome including ≥1 of the following: perinatal mortality, confirmed sepsis, grade III or IV intraventricular hemorrhage, retinopathy of prematurity, respiratory distress syndrome, and bronchopulmonary dysplasia. There were planned subgroup analyses by cerclage indication, progestogen type (vaginal progesterone vs 17-hydroxyprogesterone caproate), preterm birth history, and site. Continuous variables were compared in adjusted analyses with analysis of covariance, and categorical variables were compared with multivariable logistic regression, adjusting for potential confounders with adjusted odds ratio. A Cox regression survival curve was generated to compare latency to spontaneous delivery, censored after 37 weeks.

RESULTS

During the study period, a total of 699 singletons met the inclusion criteria: 561 in the progestogen with cerclage group and 138 with cerclage alone. Baseline characteristics were similar, except the higher likelihood of previous spontaneous preterm birth in the progestogen group (61% vs 41%; P<.001). Within the progestogen group, 52% were on 17-hydroxyprogesterone caproate weekly, 44% on vaginal progesterone daily, and 3% on oral progesterone daily. Progestogen with cerclage was associated with a significantly lower frequency of spontaneous preterm birth <37 weeks (31% vs 39%; adjusted odds ratio, 0.59 [0.39-0.89]; P=.01) and <34 weeks (19% vs 27%; adjusted odds ratio, 0.55 [0.35-0.87]; P=.01), increased latency to spontaneous delivery (hazard ratio for spontaneous preterm birth <37 weeks, 0.66 [0.49-0.90]; P=.009), and lower frequency of perinatal death (7% vs 16%; adjusted odds ratio, 0.37 [0.20-0.67]; P=.001). In planned subgroup analyses, association with reduced odds of preterm birth <37 weeks persisted in those on vaginal progesterone, those without a previous preterm birth, those with ultrasound- or examination-indicated cerclage, those who started progestogen therapy before cerclage, and in sites restricted to the United States.

CONCLUSION

Use of progestogen with cerclage was associated with reduced rates of spontaneous preterm birth and early spontaneous preterm birth compared with cerclage alone. Although this study was not sufficiently powered for subgroup analysis, the strength of evidence for benefit appeared greatest for those with ultrasound- or examination-indicated cerclage, and with vaginal progesterone.

Oral micronized progesterone versus vaginal progesterone for luteal phase support in fresh embryo transfer cycles: a multicenter, randomized, non-inferiority trial

STUDY QUESTION

Does oral micronized progesterone result in a non-inferior ongoing pregnancy rate compared to vaginal progesterone gel as luteal phase support (LPS) in fresh embryo transfer cycles?

SUMMARY ANSWER

The ongoing pregnancy rate in the group administered oral micronized progesterone 400 mg per day was non-inferior to that in the group administered vaginal progesterone gel 90 mg per day.

WHAT IS KNOWN ALREADY

LPS is an integrated component of fresh IVF, for which an optimal treatment regimen is still lacking. The high cost and administration route of the commonly used vaginal progesterone make it less acceptable than oral micronized progesterone; however, the efficacy of oral micronized progesterone is unclear owing to concerns regarding its low bioavailability after the hepatic first pass.

STUDY DESIGN, SIZE, DURATION

This non-inferiority randomized trial was conducted in eight academic fertility centers in China from November 2018 to November 2019. The follow-up was completed in April 2021.

PARTICIPANTS/MATERIALS, SETTING, METHODS

A total of 1310 infertile women who underwent their first or second IVF cycles were enrolled. On the day of hCG administration, the patients were randomly assigned to one of three groups for LPS: oral micronized progesterone 400 mg/day (n = 430), oral micronized progesterone 600 mg/day (n = 440) or vaginal progesterone 90 mg/day (n = 440). LPS was started on the day of oocyte retrieval and continued till 11-12 weeks of gestation. The primary outcome was the rate of ongoing pregnancy.

MAIN RESULTS AND THE ROLE OF CHANCE

In the intention-to-treat analysis, the rate of ongoing pregnancy in the oral micronized progesterone 400 mg/day group was non-inferior to that of the vaginal progesterone gel group [35.3% versus 38.0%, absolute difference (AD): -2.6%; 95% CI: -9.0% to 3.8%, P-value for non-inferiority test: 0.010]. There was insufficient evidence to support the non-inferiority in the rate of ongoing pregnancy between the oral micronized progesterone 600 mg/day group and the vaginal progesterone gel group (31.6% versus 38.0%, AD: -6.4%; 95% CI: -12.6% to -0.1%, P-value for non-inferiority test: 0.130). In addition, we did not observe a statistically significant difference in the rate of live births between the groups.

LIMITATIONS, REASONS FOR CAUTION

The primary outcome of our trial was the ongoing pregnancy rate; however, the live birth rate may be of greater clinical interest. Although the results did not show a difference in the rate of live births, they should be confirmed by further trials with larger sample sizes. In addition, in this study, final oocyte maturation was triggered by hCG, and the findings may not be extrapolatable to cycles with gonadotropin-releasing hormone agonist triggers.

WIDER IMPLICATIONS OF THE FINDINGS

Oral micronized progesterone 400 mg/day may be an alternative to vaginal progesterone gel in patients reluctant to accept the vaginal route of administration. However, whether a higher dose of oral micronized progesterone is associated with a poorer pregnancy rate or a higher rate of preterm delivery warrants further investigation.

STUDY FUNDING/COMPETING INTEREST(S)

This research was supported by a grant from the National Natural Science Foundation of China (82071718). None of the authors have any conflicts of interest to declare.

TRIAL REGISTRATION NUMBER

This trial was registered at the Chinese Clinical Trial Registry (http://www.chictr.org.cn/) with the number ChiCTR1800015958.

TRIAL REGISTRATION DATE

May 2018.

DATE OF FIRST PATIENT’S ENROLMENT

November 2018.

Vaginal progesterone for the prevention of recurrent spontaneous preterm birth

After the United States Food and Drug Administration pulled 17-alpha hydroxyprogesterone caproate from the market for its use in prevention of recurrent spontaneous preterm birth, national societies have had mixed recommendations regarding the management of patients with a singleton pregnancy and previous spontaneous preterm birth. Herein we highlight the randomized trial data and translational evidence supporting the use of vaginal progesterone for prevention of recurrent spontaneous preterm birth in singleton pregnancies. Prophylactic vaginal progesterone starting at 16 weeks and 0 days every night should be offered to patients with singletons and previous singleton spontaneous preterm birth regardless of cervical length, and continued along with placement of cerclage if a transvaginal ultrasound cervical length ≤25 mm is detected at <24 weeks.

Advances in progesterone delivery systems: Still work in progress?

Progesterone is a natural steroidal sex hormone in the human body, mainly secreted through the adrenal cortex, ovary, and placenta. In humans, progesterone is essential for endometrium transformation in the uterus at the time of ovulation and maintenance of pregnancy. When the body cannot produce enough progesterone for specific ailments, it is administered via different routes such as oral, vaginal, transdermal, topical, parental, and intranasal routes. Although progesterone is commercially available in multiple conventional formulations, low solubility, less permeability and extensive hepatic first-pass metabolism are the major constraints to its delivery. These challenges can be overcome substantially by formulating progesterone into novel delivery systems like lipid carriers, polymeric carriers, hydrogels, several nanocarriers, depot and controlled release systems. Various research papers and patents have been published in the last two decades on progesterone delivery systems; clinical studies were conducted to establish safety and efficacy. This review is focused on the pharmacodynamic and pharmacokinetic parameters of progesterone, its delivery constraints, and various advanced delivery systems of progesterone.

Obstetric Indications for Progestin Therapy

Specifically, meta-analyses of randomized trials demonstrate that vaginal progesterone reduces the risk of preterm birth in selected high-risk singleton pregnancies. 17-OHPC may also reduce the risk of recurrent preterm birth in singletons. Finally, one trial suggests that vaginal progesterone may also be beneficial in improving live birth rates in singletons with prior miscarriages and early pregnancy bleeding.

Vaginal progesterone compared with intramuscular 17-alpha-hydroxyprogesterone caproate for prevention of recurrent preterm birth in singleton gestations: a systematic review and meta-analysis

OBJECTIVE

Randomized trials have found benefits of both vaginal progesterone and 17-alpha-hydroxyprogesterone caproate in the prevention of recurrent preterm birth. A previous meta-analysis directly comparing the two was limited by low-quality evidence, and national and international society guidelines remain conflicting regarding progestin formulation recommended for prevention of recurrent preterm birth. The aim of this updated systematic review with meta-analysis was to evaluate the efficacy of vaginal progesterone compared with 17-alpha-hydroxyprogesterone caproate in the prevention of spontaneous preterm birth in patients with singleton gestations and previous spontaneous preterm birth.

DATA SOURCES

Searches were performed in MEDLINE, Ovid, Scopus, ClinicalTrials.gov, the International Prospective Register of Systematic Reviews (PROSPERO), SciELO, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) with the use of a combination of keywords and text words related to "preterm birth," "preterm delivery," "singleton," "cervical length," "progesterone," "progestogens," "vaginal," "17-alpha-hydroxy-progesterone caproate," and "intramuscular" from inception of each database to September 2021. No restrictions for language or geographic location were applied.

STUDY ELIGIBILITY CRITERIA

We included all randomized controlled trials of asymptomatic singleton gestations with previous spontaneous preterm birth that were randomized to prophylactic treatment with either vaginal progesterone (ie, intervention group) or intramuscular 17-alpha-hydroxyprogesterone caproate (ie, comparison group). Post hoc sensitivity analysis was performed for studies with low risk of bias and studies with protocol registration.

METHODS

The primary outcome was preterm birth <34 weeks' gestation. The summary measures were reported as relative risks with 95% confidence intervals.

RESULTS

Seven randomized controlled trials including 1910 patients were included in the meta-analysis. Patients who received vaginal progesterone had a significantly lower rate of preterm birth at <34 weeks (14.7% vs 19.9%; relative risk, 0.74; 95% confidence interval, 0.57-0.96), preterm birth at <37 weeks (36.0% vs 46.6%; relative risk, 0.76; 95% confidence interval, 0.69-0.85), and preterm birth at <32 weeks of gestation (7.9% vs 13.6%; relative risk, 0.58; 95% confidence interval, 0.39-0.86), compared with women who received intramuscular 17-alpha-hydroxyprogesterone caproate. There were no significant differences in the rate of preterm birth at <28 weeks' gestation. Adverse drug reactions were significantly lower in the vaginal progesterone group than in the 17-alpha-hydroxyprogesterone caproate group (15.6% vs 22.2%; relative risk, 0.71; 95% confidence interval, 0.54-0.92). Perinatal mortality was lower in the vaginal progesterone group than in the 17-alpha-hydroxyprogesterone caproate group (2.2% vs 4.4%; relative risk, 0.51; 95% confidence interval, 0.25-1.01). In sensitivity analysis including trials rated with at least 4 Cochrane tools as of "low risk of bias," 4 trials were included (N=575), and there was no longer a significant difference in preterm birth at <34 weeks' gestation between vaginal progesterone and 17-alpha-hydroxyprogesterone caproate (12.2% vs 13.9%; relative risk, 0.87; 95% confidence interval, 0.57-1.32).

CONCLUSION

Overall, vaginal progesterone was superior to 17-alpha-hydroxyprogesterone caproate in the prevention of preterm birth at <34 weeks' gestation in singleton pregnancies with previous spontaneous preterm birth. Although sensitivity analysis of high-fidelity studies showed the same trend, findings were no longer statistically significant.

Vaginal progesterone vs intramuscular 17-hydroxyprogesterone caproate for prevention of recurrent preterm birth: a randomized controlled trial

BACKGROUND

Preterm birth is the leading cause of neonatal morbidity and mortality, and previous preterm birth is one of the strongest risk factors for preterm birth. National and international obstetrical societies have different recommendations regarding progesterone formulation for the prevention of recurrent preterm birth.

OBJECTIVE

This study aimed to determine whether vaginal progesterone is superior to 17-hydroxyprogesterone caproate in the prevention of recurrent preterm birth in patients with singleton pregnancies who had a previous spontaneous preterm birth.

STUDY DESIGN

This was an open-label multicenter pragmatic randomized controlled trial at 5 US centers of patients with singleton pregnancies at <24 weeks of gestation who had a previous spontaneous preterm birth randomized 1:1 to either 200 mg vaginal progesterone suppository nightly or 250 mg intramuscular 17-hydroxyprogesterone caproate weekly from 16 to 36 weeks of gestation. Based on the estimated recurrent preterm birth rate of 36% with 17-hydroxyprogesterone caproate, 95 participants were needed in each arm to detect a 50% reduction in preterm birth rate with vaginal progesterone, with 80% power and 2-sided alpha of 0.05. The primary outcome was preterm birth at <37 weeks of gestation. Prespecified secondary outcomes included preterm birth at <34 and <28 weeks of gestation, mean gestational age at delivery, neonatal morbidity and mortality, and measures of adherence. Analysis was by intention to treat. The chi-square test and Student t test were used as appropriate. P<.05 was considered significant.

RESULTS

Overall, 205 participants were randomized; 94 participants in the vaginal progesterone group and 94 participants in 17-hydroxyprogesterone caproate group were included. Although gestational age at enrollment was similar, those assigned to vaginal progesterone initiated therapy earlier (16.9±1.4 vs 17.8±2.5 weeks; P=.001). Overall continuation of assigned formulation until delivery was similar (73% vs 69%; P=.61). There was no significant difference in preterm birth at <37 (31% vs 38%; P=.28; relative risk, 0.81 [95% confidence interval, 0.54-1.20]), <34 (9.6% vs 14.9%; P=.26; relative risk, 0.64 [95% confidence interval, 0.29-1.41]), or <28 (1.1% vs 4.3%; P=.37; relative risk, 0.25 [95% confidence interval, 0.03-2.20]) weeks of gestation. Participants in the vaginal progesterone group had a later mean gestational age at delivery than participants in the 17-hydroxyprogesterone caproate group (37.36±2.72 vs 36.34±4.10 weeks; mean difference, 1.02 [95% confidence interval, 0.01-2.01]; P=.047).

CONCLUSION

Vaginal progesterone did not reduce the risk of recurrent preterm birth by 50% compared with 17-OHPC; however, vaginal progesterone may lead to increased latency to delivery. This trial was underpowered to detect a smaller, but still clinically significant, difference in the efficacy of preterm birth prevention. Patient factors that impact adherence and ability to obtain medication in a timely fashion should be included in counseling on progesterone selection.

Progesterone modulates CD4+ CD25+ FoxP3+ regulatory T Cells and TGF-β1 in the maternal-fetal interface of the late pregnant mouse

OBJECTIVE

Progesterone supplementation is recommended to prevent spontaneous preterm birth (sPTB) in clinical practice. However, the exact mechanism is still unclear. This study aims to better understand the mechanisms that progesterone can prevent PTB.

METHODS

Late pregnant mice were given various doses of progesterone receptor antagonist mifepristone, and pregnancy outcomes were observed. Then, non-pregnant and pregnant mice were given a subcutaneous injection of 40 mg/kg progesterone and 5 mg/kg mifepristone, respectively. CD4⁺ CD25⁺ FoxP3⁺ Treg cells in peripheral blood and decidua basalis were detected by FACS. Expressions of FoxP3 and TGF-β1 in the decidua basalis were detected.

RESULTS

Mifepristone induced preterm birth, and an obvious dose-response was found. Proportions of CD4⁺ CD25⁺ FoxP3⁺ Treg cells in the peripheral blood of non-pregnant mice increased significantly after progesterone injection. CD4⁺ CD25⁺ FoxP3⁺ Treg cells in the peripheral blood of pregnant mice increased significantly compared with those of non-pregnant mice. In pregnant mice, mifepristone significantly decreased the proportions of CD4⁺ CD25⁺ FoxP3⁺ Treg cells in peripheral blood, and reduced proportions of Treg cells at the maternal-fetal interface and expressions of FoxP3 and TGF-β1 in the maternal-fetal interface. Total 40 mg/kg of progesterone did not increase CD4⁺ CD25⁺ FoxP3⁺ Treg in the peripheral blood of pregnant mice, but increased proportions of Treg cells at the maternal-fetal interface and up-regulated FoxP3 and TGF-β1 expressions in the maternal-fetal interface.

CONCLUSION

Progesterone promotes pregnancy immune homeostasis by up-regulating Treg cells and TGF-β1 expression in the maternal-fetal interface. It may be one of the mechanisms of progesterone in preventing sPTB.

Pharmacokinetics, safety and bioequivalence of two formulations of progesterone soft capsule in healthy Chinese postmenopausal females: Impacts of a high-fat meal

Progesterone is an important natural hormone regulating ovulation and menstruation. The present study aimed to investigate the pharmacokinetics and safety of two formulations of progesterone in Chinese postmenopausal females under fasting and fed conditions. The study adopted a single-dose, open-label, randomized, three-period bioequivalence design. A total of 96 subjects were enrolled and randomly assigned to the fasting cohort or fed cohort. A high-fat meal (890 kcal) was used in the fed study. The reference-scaled average bioequivalence method was used for bioequivalence evaluation. A high-fat meal led to a 22-fold higher peak concentration (C_max ) and a 7-fold higher area under the curve (AUC) while time to reach C_max and half-life was not significantly affected. The concentration-time curve displayed double peaks suggesting the existence of enterohepatic circulation. The test/reference geometric mean ratios for C_max and AUC under fasting and fed conditions are all within the range of 80% to 125%. All adverse events (AEs) that occurred during the trial were mild and did not cause drop-out, though these AEs occurred more frequently under fed state. In conclusion, the two formulations of progesterone are bioequivalent in Chinese subjects under fasting and fed conditions. Drug label modification regarding food effects needs further discussion.

Micronized progesterone plus dydrogesterone versus micronized progesterone alone for luteal phase support in frozen-thawed cycles (MIDRONE): a prospective cohort study

STUDY QUESTION

Does the addition of oral dydrogesterone to vaginal progesterone as luteal phase support improve pregnancy outcomes during frozen embryo transfer (FET) cycles compared with vaginal progesterone alone?

SUMMARY ANSWER

Luteal phase support with oral dydrogesterone added to vaginal progesterone had a higher live birth rate and lower miscarriage rate compared with vaginal progesterone alone.

WHAT IS KNOWN ALREADY

Progesterone is an important hormone that triggers secretory transformation of the endometrium to allow implantation of the embryo. During IVF, exogenous progesterone is administered for luteal phase support. However, there is wide inter-individual variation in absorption of progesterone via the vaginal wall. Oral dydrogesterone is effective and well tolerated when used to provide luteal phase support after fresh embryo transfer. However, there are currently no data on the effectiveness of luteal phase support with the combination of dydrogesterone with vaginal micronized progesterone compared with vaginal micronized progesterone after FET.

STUDY DESIGN, SIZE, DURATION

Prospective cohort study conducted at an academic infertility center in Vietnam from 26 June 2019 to 30 March 2020.

PARTICIPANTS/MATERIALS, SETTING, METHODS

We studied 1364 women undergoing IVF with FET. Luteal support was started when endometrial thickness reached ≥8 mm. The luteal support regimen was either vaginal micronized progesterone 400 mg twice daily plus oral dydrogesterone 10 mg twice daily (second part of the study) or vaginal micronized progesterone 400 mg twice daily (first 4 months of the study). In women with a positive pregnancy test, the appropriate luteal phase support regimen was continued until 7 weeks' gestation. The primary endpoint was live birth after the first FET of the started cycle, with miscarriage <12 weeks as one of the secondary endpoints.

MAIN RESULTS AND THE ROLE OF CHANCE

The vaginal progesterone + dydrogesterone group and vaginal progesterone groups included 732 and 632 participants, respectively. Live birth rates were 46.3% versus 41.3%, respectively (rate ratio [RR] 1.12, 95% CI 0.99-1.27, P = 0.06; multivariate analysis RR 1.30 (95% CI 1.01-1.68), P = 0.042), with a statistically significant lower rate of miscarriage at <12 weeks in the progesterone + dydrogesterone versus progesterone group (3.4% versus 6.6%; RR 0.51, 95% CI 0.32-0.83; P = 0.009). Birth weight of both singletons (2971.0 ± 628.4 versus 3118.8 ± 559.2 g; P = 0.004) and twins (2175.5 ± 494.8 versus 2494.2 ± 584.7; P = 0.002) was significantly lower in the progesterone plus dydrogesterone versus progesterone group.

LIMITATIONS, REASONS FOR CAUTION

The main limitations of the study were the open-label design and the non-randomized nature of the sequential administration of study treatments. However, our systematic comparison of the two strategies was able to be performed much more rapidly than a conventional randomized controlled trial. In addition, the single ethnicity population limits external generalizability.

WIDER IMPLICATIONS OF THE FINDINGS

Our findings study suggest a role for oral dydrogesterone in addition to vaginal progesterone as luteal phase support in FET cycles to reduce the miscarriage rate and improve the live birth rate. Carefully planned prospective cohort studies with limited bias could be used as an alternative to randomized controlled clinical trials to inform clinical practice.

STUDY FUNDING/COMPETING INTERESTS

This study received no external funding. LNV has received speaker and conference fees from Merck, grant, speaker and conference fees from Merck Sharpe and Dohme, and speaker, conference and scientific board fees from Ferring; TMH has received speaker fees from Merck, Merck Sharp and Dohme, and Ferring; R.J.N. has received scientific board fees from Ferring and receives grant funding from the National Health and Medical Research Council (NHMRC) of Australia; BWM has acted as a paid consultant to Merck, ObsEva and Guerbet, and is the recipient of grant money from an NHMRC Investigator Grant.

TRIAL REGISTRATION NUMBER

NCT0399876.

Predictors of Early Preterm Birth Despite Vaginal Progesterone Therapy in Singletons with Short Cervix

OBJECTIVE

This study aimed to identify the incidence of and risk factors for early preterm birth (PTB) (delivery <34 weeks) in women without prior PTB and current short cervix (≤20 mm) prescribed vaginal progesterone.

STUDY DESIGN

Retrospective cohort study of singletons without prior PTB diagnosed with short cervix (≤20 mm) between 18^0/7 and 23^6/7 weeks. Women who accepted vaginal progesterone and had delivery outcomes available were included. Demographic/obstetric history, cervical length, and pregnancy characteristics compared between women with early PTB versus delivery ≥34 weeks. Multiple logistic regression analysis used to identify predictors; odds ratio for significant factors used to generate a risk score. Risk score and risk of early PTB assessed with receiver operating characteristic curve (ROCC). Perinatal outcomes compared by risk score.

RESULTS

Among 109 patients included, 29 (27%) had a spontaneous PTB <34 weeks. In univariate analysis, only gestational age at ultrasound, presence funneling, and mean cervical length were significantly different between those with and without early sPTB. With multiple logistic regression analysis, only gestational age at diagnosis (odds ratio [OR]: 0.66; 95% confidence interval [CI]: 0.46-0.96; p = 0.028) and index cervical length (OR: 0.84; 95% CI: 0.76-0.93; p = 0.001) remained significantly associated with early PTB. ROCC for the risk score incorporating cervical length and gestational age was predictive of early PTB with an AUC of 0.76 (95% CI: 0.67-0.86; p < 0.001). A high-risk score was predictive of early PTB with a sensitivity of 79%, specificity of 75%, positive predictive value of 54%, and negative predictive value of 91%. Women with a high-risk score had worse perinatal outcomes compared with those with low-risk score.

CONCLUSION

A total of 27% of patients with short cervix prescribed vaginal progesterone will have a sPTB < 34 weeks. Patients at high risk for early PTB despite vaginal progesterone therapy may be identified using gestational age and cervical length at diagnosis of short cervix. Given the narrow window for intervention after diagnosis of short cervix, this has important implications for clinical care.

Progesterone Intramuscularly or Vaginally Administration May Not Change Live Birth Rate or Neonatal Outcomes in Artificial Frozen-Thawed Embryo Transfer Cycles

BACKGROUNDS

Previous studies suggested that singletons from frozen-thawed embryo transfer (FET) were associated with higher risk of large, post-date babies and adverse obstetrical outcomes compared to fresh transfer and natural pregnancy. No data available revealed whether the adverse perinatal outcomes were associated with aberrantly high progesterone level from different endometrium preparations in HRT-FET cycle. This study aimed to compare the impact of progesterone intramuscularly and vaginally regimens on neonatal outcomes in HRT-FET cycles.

METHODS

A total of 856 HRT-FET cycles from a fertility center from 2015 to 2018 were retrospectively analyzed. All patients had their first FET with two cleavage-staged embryos transferred. Endometrial preparation was performed with sequential administration of estrogen followed by progesterone intramuscularly 60 mg per day or vaginal gel Crinone 90 mg per day. Pregnancy outcomes including live birth rate, singleton birthweight, large for gestational age (LGA) rate, small for gestational age (SGA) rate, and preterm delivery rate were analyzed. Student's t test, Mann-Whitney U-test, Chi square analysis, and multivariable logistic regression were used where appropriate. Differences were considered significant if p < 0.05.

RESULTS

No significant difference of live birth rate was found between different progesterone regimens (Adjusted OR 1.128, 95% CI 0.842, 1.511, p = 0.420). Neonatal outcomes like singleton birthweight (p = 0.744), preterm delivery rate (Adjusted OR 1.920, 95% CI 0.603, 6.11, p = 0.269), SGA (Adjusted OR 0.227, 95% CI 0.027, 1.934, p = 0.175), and LGA rate (Adjusted OR 0.862, 95% CI 0.425, 1.749, p=0.681) were not different between two progesterone regimens. Serum P level >41.82 pmol/L at 14 day post-FET was associated with higher live birth rate than serum P level ≤41.82 pmol/L in HRT-FET cycles when progesterone was intramuscularly delivered (Adjusted OR 1.690, 95% CI 1.002, 2.849, p = 0.049). But singleton birthweight, preterm delivery rate, SGA and LGA rate were not different between these two groups.

CONCLUSIONS

Relatively higher serum progesterone level induced by intramuscular regimen did not change live birth rate or neonatal outcomes compared to vaginal regimen. Monitoring serum progesterone level and optimizing progesterone dose of intramuscular progesterone as needed in HRT-FET cycles has a role in improving live birth rate without impact on neonatal outcomes.