BACKGROUND: Makena (17-hydroxyprogesterone caproate) was approved by the United States Food and Drug Administration for the prevention of recurrent spontaneous preterm birth in 2011 under the accelerated approval pathway, but fundamental pharmacokinetic or pharmacodynamic (Phase 1 and Phase 2) studies were not performed. At the time, there were no dose-response or concentration-response data. The therapeutic concentration was not known. The lack of such data brings into question the dosing regimen for 17-hydroxyprogesterone caproate and if it was optimized.
OBJECTIVE: The purpose of this study was to evaluate the dosing regimen for 17-hydroxyprogesterone by analyzing 3 data sets in which the 17-hydroxyprogesterone caproate pharmacology was evaluated, namely the Maternal-Fetal Medicine Omega 3 study, the Obstetric-Fetal Pharmacology Research Units study, and the Obstetrical-Fetal Pharmacology Research Centers study. If an inappropriate dosing regimen could be identified, such information could inform future studies of pharmacotherapy in pregnancy.
METHODS: Data from the Omega 3 study were used to determine if plasma concentration was related to spontaneous preterm birth risk and if a threshold concentration could be identified. Data from the Obstetric-Fetal Pharmacology Research Units study were used to determine the half-life of 17-hydroxyprogesterone caproate and to develop a model to simulate drug concentrations with various dosing regimens. Data from the Obstetrical-Fetal Pharmacology Research Centers study were used to determine the relationship between dose and safety outcomes.
RESULTS: Analysis of the Omega 3 data set indicated that the risk for spontaneous preterm birth decreased as the log concentration of 17-hydroxyprogesterone caproate increased (odds ratio, 0.04; 95% confidence interval, 0.00-0.90). A steady state concentration of >9 ng/mL (equivalent to >8 ng/mL at 25-28 weeks) was associated with the lowest risk for spontaneous preterm birth (hazard ratio, 0.52; 95% confidence interval, 0.27-0.98; P=.04); this concentration was not achieved in 25% of subjects who received the 250 mg weekly dose. In the Obstetrical-Fetal Pharmacology Research Units study, the adjusted half-life (median and interquartile range) of 17-hydroxyprogesterone caproate was 14.0 (11.5-17.2) days. Simulations indicated that with the 250 mg weekly dose, >5 weekly injections were required to reach the 9 ng/mL target; however, those with the shortest half-life (corresponding to higher clearance), never reached the targeted 9 ng/mL concentration. In 75% of subjects, a loading dose of 500 mg weekly for 2 weeks followed by 250 mg weekly achieved and maintained the 9 ng/mL concentration within 2 weeks but in those 25% with the shortest half-life, concentrations exceeded the 9 ng/mL target for only 3 weeks. In the Obstetrical-Fetal Pharmacology Research Centers study, all 65 subjects who received a weekly dose of 500 mg exceeded the 9 ng/mL steady state.
CONCLUSIONS: The dosing regimen for 17-hydroxyprogesterone caproate was inadequate. There is a significant inverse relationship between drug concentration and spontaneous preterm birth. The risk was lowest when the concentration exceeded 9 ng/mL, but 25% of women who received the 250 mg weekly dose never reached or maintained this concentration. The drug\'s long half-life necessitates a loading dose to achieve therapeutic concentrations rapidly. The omission of basic pharmacologic studies to determine the proper dosing may have compromised the effectiveness of 17-hydroxyprogesterone caproate. Future pharmacotherapy trials in pregnancy must first complete fundamental pharmacology studies.

Our objective was to evaluate whether pregnancy is prolonged by the use of a proteomics-based maternal serum screening test followed by treatment interventions. This is a secondary analysis of the PREVENT-PTB randomized trial comparing screening with the PreTRM test versus no screening. The primary trial analysis found no significant between-group difference in the preterm birth rate. Rather than considering a dichotomous outcome (preterm versus term), we treated gestational age at birth as a continuous variable using survival analysis. We also evaluated between-group difference in NICU length of stay and duration of respiratory support. Results indicated that pregnancy was significantly prolonged in subjects screened with the PreTRM test compared to controls (adjusted hazard ratio 0.53, 95% confidence interval 0.36-0.78, p < 0.01). Newborns of screened subjects had significantly shorter NICU stays but no significant decrease in duration of respiratory support. In the PreTRM screen-positive group, interventions that were associated with pregnancy prolongation included care management and low-dose aspirin but not 17-hydroxyprogesterone caproate. We conclude that screening with the PreTRM test followed by interventions for screen-positive pregnancies may prolong pregnancy and reduce NICU LOS, but these observations need to be confirmed by additional research.

The effectiveness of 17-hydroxyprogesterone caproate is unclear as trials have provided conflicting results. With the absence of fundamental pharmacologic studies addressing dosing or the relationship between drug concentration and gestational age at delivery, the effectiveness of the medication cannot be evaluated.
This study aimed to evaluate the relationship between plasma concentrations of 17-hydroxyprogesterone caproate and preterm birth rates and gestational age at preterm delivery and to assess the safety of the 500-mg dose.
This study recruited 2 cohorts with previous spontaneous preterm birth; 1 cohort (n=143) was randomly assigned to either 250-mg or 500-mg 17-hydroxyprogesterone caproate, and the other cohort (n=16) was receiving the 250-mg dose for routine care. Steady-state trough plasma concentrations of 17-hydroxyprogesterone caproate obtained at 26 to 30 weeks of gestation were correlated to dose, spontaneous preterm birth rates, and measures of gestational length. Furthermore, maternal and neonatal safety outcomes were evaluated according to dose.
There was a dose proportional increase in trough plasma concentrations with the 250-mg (median, 8.6 ng/m; n=66) and 500-mg (median, 16.2 ng/mL; n=55) doses. In 116 compliant participants with blood samples, drug concentration was not related to the spontaneous preterm birth rate (odds ratio, 1.00; 95% confidence interval, 0.93-1.08). However, there was a significant relationship between drug concentration and both the interval from the first administration to delivery (interval A: coefficient, 1.11; 95% confidence interval, 0.00-2.23; P=.05) and the interval from the 26- to 30-week blood draw to delivery (interval B: coefficient, 1.56; 95% confidence interval, 0.25-2.87; P=.02). The spontaneous preterm birth rate or measures of gestational length were not related to dose. Postenrollment cerclage adversely affected all pharmacodynamic assessments because it was a powerful predictor of spontaneous preterm birth (odds ratio, 4.03; 95% confidence interval, 1.24-13.19; P=.021) and both measures of gestational length (interval A [coefficient, -14.9; 95% confidence interval, -26.3 to -3.4; P=.011] and interval B [coefficient, -15.9; 95% confidence interval, -25.8 to -5.9; P=.002]). Initial cervical length was significantly related to the risk of postenrollment cerclage (odds ratio, 0.80; 95% confidence interval, 0.70-0.92; P=.001). Maternal and neonatal safety outcomes were similar in both dosing groups.
In this pharmacodynamic study, trough plasma 17-hydroxyprogesterone caproate concentrations were significantly associated with gestational age at preterm birth but not with the preterm birth rate. Postenrollment cerclage was a powerful predictor of spontaneous preterm birth rate and gestational length. Initial cervical length predicted the risk of postenrollment cerclage. Adverse events were similar with the 500-mg and 250-mg doses of 17-hydroxyprogesterone caproate.

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.

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.
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.
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.
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).
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.

Obstetrical healthcare providers frequently field questions about the safety of medications recommended or prescribed to their pregnant patients. Most women use as least 1 medication during pregnancy; however, there is little information about the safety or appropriate dosing of many medications during this phase of life. In addition, the development of drugs for use in pregnant women trails behind the development of drugs intended for other sectors of the population. Our goal is to inform the obstetrics community about the US Food and Drug Administration authority and their role in approving drugs for marketing. We begin with the statutes that led to the creation of the Food and Drug Administration and its current organization. We then cover drug development and the Food and Drug Administration review process, including the role of the advisory committee. The different types of drug approvals are discussed, with some specific examples. Finally, we enumerate the drugs specifically approved for use in obstetrics and contrast them with drugs commonly used by pregnant women and drugs used \"off-label\" during pregnancy. The Food and Drug Administration is committed to protecting and advancing the public health of pregnant women by guiding the development and ensuring the availability of effective and safe therapeutics for obstetrical indications and for medical conditions during pregnancy. We hope this review will inspire more research addressing drug use during pregnancy.

Progesterone has been used for preventing preterm birth with mixed results. The American College of Obstetricians and Gynecologists and Society for Maternal-Fetal Medicine recommended the use of 17-hydroxyprogesterone caproate for risk reduction of recurrent spontaneous preterm birth based on the results of a multicenter, randomized trial in the United States. However, recent literature lacks consensus for efficacy in the American population. In addition, partial adherence and outcomes thereof are underreported. Hence, the relationship between practical adherence to 17-hydroxyprogesterone caproate and outcomes were evaluated.
The objective of this study was to evaluate the adherence to 17-hydroxyprogesterone caproate, defined as receipt of greater than 80% of intended injections, at an outpatient maternal-fetal medicine center and its effect on maternal and neonatal outcomes.
This retrospective cohort study included women older than 18 years with a singleton gestation, history of spontaneous preterm birth who initiated 17-hydroxyprogesterone caproate weekly injections between 16 and 20 weeks\' gestational age and delivered between the years 2014 and 2017. Women receiving 17-hydroxyprogesterone caproate injections outside of the clinic were excluded. The primary outcome of adherence and secondary outcomes of gestational age at delivery, birthweight, and neonatal outcomes were analyzed using descriptive data, independent t-test, Mann-Whitney U test, chi-square test, and Fisher exact test, where appropriate, with a P value <.05 being considered significant.
Adherence to 17-hydroxyprogesterone caproate occurred in 38 of 92 (41.3%) women included in the study. At baseline, there was a difference in age between groups of adherent and nonadherent women (adherent: 30.8 years; nonadherent: 27.4 years; P=.002). The rate of spontaneous preterm birth less than 37, 35, and 32 weeks were not significantly different in those who were adherent vs nonadherent to 17-hydroxyprogesterone caproate. There were no differences in gestational age at delivery (adherent: 36.8±2.6 weeks; nonadherent: 36.5±3.8 weeks; P=.66), birthweight (adherent: 2776 g; nonadherent: 2709 g; P=.68), or composite neonatal morbidity (adherent: 18.4%; nonadherent: 20.4%; P=.86) between the adherent and nonadherent groups. Neonatal intensive care unit length of stay was 15.5 days in the adherent group compared with 15 days in the nonadherent group (P=.72).
Real-world adherence to 17-hydroxyprogesterone caproate is suboptimal with less than half of women adherent to in-clinic administration. Adherence to 17-hydroxyprogesterone caproate was not associated with a difference in gestational age at delivery or birthweight compared with nonadherence. Further studies are needed to assess the outpatient administration and benefit of 17-hydroxyprogesterone caproate therapy.

Preeclampsia (PE) is new onset hypertension during pregnancy associated with increased uterine artery resistance (UARI) and an imbalance among CD4 + T lymphocytes and natural killer (NK) cells. We have shown an important role for 17-hydroxyprogesterone caproate (17-OHPC) to improve hypertension and fetal demise in the RUPP rat model of PE. However we have not examined a role for 17-OHPC to improve NK cells and CD4+TH2 cells as possible mechanisms for improved fetal weight and hypertension. Therefore, we hypothesized that 17-OHPC lowers NK cells while improving the T cell ratio in the RUPP rat. RUPP was surgically induced on gestational day 14 in pregnant rats. 17-OHPC (3.32 mg/kg) was administered intraperitoneal on day 15, UARI was measured on day 18. Blood pressure (MAP), blood and tissues were collected on GD 19. MAP in NP rats (n = 9) was 100 ± 2, 104 ± 6 in Sham rats (n = 8), 128 ± 2 in RUPP (n = 11) and 115 ± 3 mmHg in RUPP + 17-OHPC (n = 10), p < 0.05. Pup weight and UARI were improved after 17-OHPC. Total and cytolytic placental NK cells were 38 ± 5, and 12 ± 2% gate in RUPP rats which decreased to 1.6 ± 0.5 and 0.4 ± 0.2% gate in RUPP + 17OHPC rats. CD4+ T cells were 40 ± 3 in RUPP rats, which significantly decreased to 7 ± 1 RUPP + 17-OHPC rats. Circulating and placental TH2 cells were 6.0 ± 1, 0.3 ± 0.1% gate in RUPP rats and 12 ± 1%, 2 ± 0.5% gate in RUPP + 17-OHPC rats, p < 0.05 This study identifies new mechanisms whereby 17-OHPC improves outcomes in response to placental ischemia.

Women with a history of a preterm birth (PTB) are at high risk for recurrence. Weekly 17-hydroxyprogestrone caproate (17-P) injections can reduce the risk of recurrence in women with prior spontaneous PTB. PTB occurs disproportionately in non-Hispanic black (NHB) women, and uptake and adherence to 17-P among NHB women are lower compared to women in other racial/ethnic groups. Evidence-based interventions to improve 17-P uptake and adherence that incorporate women\'s perceptions and preferences are needed. Our objective was to identify women\'s perspectives and preferences for interventions to promote uptake of and adherence to 17-P, particularly among NHB women. We conducted an exploratory sequential mixed methods study using focus group discussions (FGDs), a survey, and in-depth interviews (IDIs). We recruited women with a history of PTB who self-identified as NHB for the FGDs and IDIs. Survey participation was open to any woman with a history of PTB regardless of their race and ethnicity. Women could only participate in one of the three data collection activities. Transcripts from the qualitative focus groups and in-depth interviews were analyzed using applied thematic analysis. Descriptive statistics was used to analyze the quantitative survey. Eighty-two women participated in the study (FGDs [n = 7], surveys [n = 60], and IDIs [n = 15]). Suggested interventions were separated into two categories: (1) clinic-based interventions (i.e., interventions delivered during the clinical encounter) and (2) community-based interventions (i.e., interventions delivered outside of the clinical encounter). Clinic level interventions included improved clinic access and scheduling, same-day appointments, appointment reminders, making the clinic experience more comfortable for patients, and encouragement from providers. Interventions at the community level included increased 17-P awareness among support persons, employers, and community members and administration of 17-P outside the clinic setting. Our findings offer multiple potential interventions that could improve uptake of and adherence to 17-P for PTB prevention among NHB women. These proposed interventions have the potential to mitigate barriers to 17-P and narrow the disparity in PTB rates. Given the alarming and increasing rates of prematurity and PTB disparities, it is imperative to test, refine, and incorporate effective interventions into clinical practice. Our findings provide insights from patients that can help shape such interventions.

To reduce the risk of recurrence, women with a history of spontaneous preterm birth (PTB) are recommended to receive 17-hydroxyprogesterone caproate (17-P) injections starting by the 20th week of pregnancy. In women eligible for 17-P, we aimed to identify patient factors and geospatial locations associated with increased risk of presentation beyond 20 weeks gestation.
We conducted a secondary analysis of a retrospective cohort study including all women meeting criteria for 17-P within a single academic medical center over a 2-year period. We compared early (< 20 6/7 weeks) with late (> 21 weeks) presenters via demographics, social history, and index pregnancy outcomes using standard and Bayesian statistical models. Geospatial mapping was performed to determine residential areas with high risk for late presentation.
Geocoded address data was available for 351 women in whom the mean gestational age at first visit was 14.9 weeks, and 63 of whom were late presenters (17.9%). Younger maternal age, current smoking, and lack of health insurance were predictors of late presentation with greater than 95% probability. Hispanic ethnicity and black race were associated with higher odds of late presentation with 87 and 69% probability, respectively. The area with the latest gestational age at presentation was located within central Durham City and to the northeast.
Our study identified patient-level risk factors and geographic locations associated with presentation beyond the recommend window for 17-P initiation. These findings suggest an urgent need for intervention to improve early prenatal care initiation and a target location where such interventions will be most impactful.