The observational HOME study has been carried out in southeastern Norway, primarily at Oslo University Hospital (OUH) in Norway's capital, Oslo, which has the largest Obstetric Department in Norway, with 8,000 deliveries annually. Another hospital in the region, Drammen Hospital, with 2,000 deliveries annually, will also recruit some patients to the study.

Norway offers pregnant women free-of-charge antenatal, delivery, and postpartum care. Women deemed at high risk for adverse pregnancy outcomes, either due to current pregnancy complications or previous adverse obstetric outcomes, are offered intensified follow-up according to a national expert guideline (3).

The observational study protocol for this study was posted on ClinicalTrials.gov in 2023 (10 March 2023: ref: NCT05763069). The first woman was recruited to the hospital-monitored group in December 2022. The first woman monitored at home was recruited in June 2024, following a 2-year period of study adaptation due to General Data Protection Regulation (GDPR) issues and technology solution developments for the transfer of home-registered data to the hospital's electronic patient journal systems.

The HOME study has involved user groups in the planning of the study, including the local hospital advisory user group and the Norwegian SIDS and Stillbirth Society. The latter society also provides advisory help during all trial phases, as a member of the steering group and as a non-academic named collaborator in the HOME study grant obtained from the Research Council of Norway (ref. 326650).

Prior to recruiting women to the HOME study, a qualitative study was conducted to address user perspectives on home-based telemonitoring as an alternative to hospital admissions and/or frequent outpatient visits. Hospitalized women with ongoing high-risk pregnancies, women with a history of stillbirth in a previous pregnancy, midwives, and obstetricians (total n = 21) were interviewed (9). The results showed that the participants not only acknowledged the benefits and potential of home monitoring but also highlighted their concerns regarding clinical safety and responsibility. Home monitoring of high-risk pregnancy was problematized in terms of personal/individual factors, such as the need for personalized training, eligibility assessments of individuals, and empowerment to undertake and cope with a more active patient role. A sense of shared responsibility was regarded as crucial to maintain safety, particularly when acute or critical situations emerge (9).

In line with these user expectations, published in 2022, we developed user instruction protocols for home monitoring training while the patient is still in the hospital. We developed clinical questionnaires regarding patient-hospital communication using smartphone platforms that were adapted to the specific pregnancy complications in the study (e.g., hypertensive disorders vs. pPROM). We also updated the instruction protocols for supervising healthcare staff in the clinical setting of home monitoring, including check lists and selection processes to identify pregnancies deemed clinically relevant for home monitoring, daily follow-up systems, electronic patient journal documentation, and the use of the most appropriate public reimbursement classifications (as none have hitherto been specifically developed for home monitoring of high-risk pregnancies).

The patients eligible for participation in the study are ≥18 years old, Norwegian-speaking, singleton pregnant women requiring intensified follow-up after at least one initial comprehensive hospital assessment. The following indications for surveillance may be relevant for home monitoring (Table 1): hypertensive disorders (chronic hypertension, gestational hypertension, and/or preeclampsia), pPROM, and previous adverse obstetric outcomes (e.g., fetal death, severe preeclampsia, preterm delivery, and/or fetal growth restriction). Exclusion criteria for home monitoring include a clinical imminent health risk to the mother and/or fetus, including (but not restricted to) non-reassuring CTG, blood pressure, infectious or clinical signs or symptoms, and/or more than 1 h travel to the hospital. Women with an expected delivery or induction of delivery within a short period will not be recruited [e.g., preeclampsia at term (≥37 weeks), prelabor rupture of membranes (PROM) ≥37 weeks, or pPROM with indication for rapid delivery (e.g., discolored amniotic fluid, suspicion of chorioamnionitis or other severe infections, or pathological CTG)]. Insufficient support at home and a lack of understanding of the relevant HOME study's technical devices (to be tested before departure from the hospital) are also exclusion criteria for being offered home monitoring.

A senior obstetrician identifies eligible pregnant women (followed up at the hospital) for home monitoring, according to the aforementioned medical inclusion and exclusion selection criteria, using a preprinted checklist. Eligible women are thereafter invited and informed by a trained research midwife, who has sufficient time with each woman to answer questions and explain the practical procedures of monitoring either in the hospital or at home. Oral and written information is provided, and written informed consent is thereafter obtained from eligible women willing to participate in the study. The timeline for participation in the study is shown in Figure 1. The midwife will, prior to study inclusion, also assess whether the woman has adequate support at home and sufficient technical understanding, including testing the patient's capability to use the specific information technology (IT) solutions necessary for home monitoring.

The allocation of women to the regular follow-up or home monitoring groups is based on technical equipment availability, as explained below.

The primary outcome variable is a composite of severe adverse events, as detailed in Table 2. These include maternal mortality, severe maternal morbidity/organ damage [e.g., sepsis, eclampsia, cerebral hemorrhage, acute respiratory distress syndrome, liver rupture, pulmonary embolism, amniotic fluid embolism, hemolysis, elevated liver enzymes, and low platelets (HELLP), HELLP without hemolysis (ELLP), and/or disseminated intravascular coagulation (DIC)], and fetal or early neonatal death. The primary composite outcome will be thoroughly evaluated by the Diagnostic Advisory Group (DAG). The members of the DAG include three senior obstetricians, one senior pediatrician, and one experienced midwife, all of whom are employed at Oslo University Hospital but are unrelated to and independent of the study group members and principal investigator (PI). All separate primary outcome events will be presented to the DAG, who will discuss and evaluate whether the events are related to the study or not, and whether the events could have been prevented or not.

The secondary study outcomes (Table 2) include maternal morbidity [chorioamnionitis and malignant hypertension (persistent systolic blood pressure ≥160 mm Hg and/or diastolic blood pressure ≥100 mmHg)] and adverse neonatal outcomes (Apgar score <7 at 5 min, cord acidemia, metabolic acidosis (18), admission to neonatal intensive care unit, and/or respirator/ventilation support treatment). Umbilical cord acid-base data will be validated according to the method described by Kro et al. (19, 20).

In addition to the daily reports, the patient-reported outcome measures in the HOME study will be collected by digital questionnaires sent to the study participants' smartphones 2–7 days after hospital admission or start of home monitoring, and again at 10–12 weeks postpartum, for study group comparison. One digital reminder will automatically be sent to non-responders. The validated questionnaires include the Bergen Insomnia Scale (21), the General Perceived Self-Efficacy Scale (22), Sense of Coherence-13 (23), Edinburgh Postnatal Depression Scale (24–26), and the 25-item version of the Hopkins Symptom Checklist (27, 28). In addition, explanatory variables for multivariable analyses will be added, including a history of depression (based on DSM-IV criteria) (26, 29) and major life events during the previous 12 months, including serious events related to marriage, family, friends, work, or health (26), selected from established life event scales (26, 30, 31). In addition, a few HOME study-specific questions/items were constructed for the particular study that are not validated. After completing the questionnaires, the participants will be informed about available help resources if they are in need of further mental support during a potentially demanding period in their life (e.g., from their primary healthcare provider or a Norwegian mental health organization that is available 24/7).

The cost of home monitoring will be compared to hospital monitoring, including the maternal costs until delivery, but excluding maternal and newborn healthcare costs after delivery. The health economics assessment will evaluate hospital costs, including costs related to health professionals and administrative personnel time, for both outpatient and inpatient care. The mean cost per outpatient consultation and inpatient hospital cost per day will be calculated. The estimated mean cost is multiplied by the number of registered contacts at different departments during the study time (until delivery). Using the overhead indirect cost method, we will calculate the average estimated mean cost for different wards where the patient has a registered contact at the Oslo University Hospital. All costs will be evaluated as if operating under steady-state conditions based on the budget of 2023. Prices will be converted from Norwegian crowns (NOK) to U.S. dollars (US$) using the mean exchange rate for 2023 of 1 US$ = 9.86 NOK. All patient costs will be covered by the Norwegian public insurance system.

The development of improved surveillance tools to detect intrapartum or antepartum fetal stress is needed to prevent neonatal adverse outcomes, as CTG has limitations. We have previously found that predelivery circulating maternal antiangiogenic protein concentrations, produced by the placenta, may improve automated alerts produced by the Oxford System for computerized intrapartum monitoring (OxSys) 1.7 prototype (32). Depending on the technical feasibility, a predelivery placenta-associated biomarker and computerized antepartum and intrapartum fetal heart rate pattern study is planned in collaboration with UK researchers using data from the women in the HOME study.

The sample size calculation is based on the non-inferiority design and will be calculated for the primary clinical composite outcome (described above and in Table 2). The non-inferiority margin was set to 10% (i.e., a difference larger than 10% will be considered clinically significant), based on careful clinical considerations. The expected proportion of the outcome was set to 10%, based on the rate of the primary composite outcome observed in the first 80 women recruited to the hospital-monitored group in the HOME study. If there is no true difference between the home-monitored and the hospital-monitored groups' primary composite outcomes (10% in both groups), a total of 224 women with high-risk pregnancies (112 women in each group) is required. With this number of participants, we have a power of 0.80, ensuring that the upper limit of a one-sided 95% confidence interval will exclude a difference in favor of the hospital-monitored group of more than 10%. An additional six women will be invited to take potential dropouts into account. Further, due to the non-parallel group design (women were not randomized to either group, but are first mainly allocated to the hospital-monitored group and then to the home monitored group, pending on availability of home monitoring resources and equipment), another 20 women will be recruited to adjust for potential confounding factors such as parity and gestational age (totalling 250; 125 women in each group).

After inclusion in the study, baseline data such as patient demographics, medical and obstetric history, and pregnancy data will be collected and registered in a case report form before entering and coding the data in a study-specific electronic record. After delivery, the remaining relevant data for the assessment of maternal mortality and morbidity and perinatal outcomes will be collected from the hospital's electronic patient journal and registered in the study-specific HOME records. All primary and secondary outcome data will be registered, in addition to gestational age at birth and birthweight (Table 2).

The composite primary outcome will be analyzed using logistic regression analyses. Parity and gestational age will be included as potential confounding variables. Further, each component of the composite primary outcome and all secondary outcomes will be analyzed to provide further insight into the research question. The results will be presented as odds ratios with 95% confidence intervals, in addition to crude proportions (not adjusting for parity and gestational age).

The obstetric experts in the DAG will independently evaluate all composite primary outcomes continuously throughout the project period and without interference from anyone in the project group. The DAG will conclude whether any primary (severe adverse) outcomes are related to the study or not, and the results will be presented in detail in the study report.

The study participants' experience, mental wellbeing (depression and anxiety), sense of coherence, and self-efficacy will be described at the group level (hospital monitoring vs. home monitoring) at the two investigated time points (2–7 days after hospital admission or start of home monitoring and again at 10–12 weeks postpartum).

The cost-effectiveness of home monitoring compared to the hospital-monitored group will be described at the group level based on the estimated cost of each admission to different wards at Oslo University Hospital and outpatient visits from inclusion in the HOME study until delivery.

The generalizability of the study sample will be evaluated by comparing the study group characteristics with the general pregnant population, the entirety of the latter being registered due to the compulsory notification of each birth to the Medical Birth Registry of Norway (33). Only women with Norwegian language skills can participate, which excludes some groups, particularly a subgroup of newly immigrated women, limiting the generalizability of the study. The present study can, however, be considered a first step in providing more personalized and flexible follow-up for women with high-risk pregnancies. If the study results are reassuring, future projects may include more heterogeneous language and ethnic groups, thus testing home monitoring opportunities in more diverse pregnant populations.