Overview: The protocol outlines the process designed to systematically review clinical practice guidelines (CPGs), addressing the antenatal management of dichorionic diamniotic (DCDA) twin pregnancies. Background: CPGs are statements that include recommendations intended to optimise patient care, that are informed by a systematic review of evidence and an assessment of the benefits and harms of alternative care options. CPGs are typically created by scientific institutes, organisations and professional societies, and high-quality CPGs are fundamental to improve patient outcomes, standardise clinical practice and improve the quality of care. While CPGs are designed to improve the quality of care, to achieve this, the identification and appraisal of current international CPGs is required. Because twin pregnancies are identified as high-risk pregnancies, a systematic review of the CPGs in this field is a useful first step for establishing the required high level of care. Aim: The aim of the systematic review is to identify, appraise and examine published CPGs for the antenatal management of DCDA twin pregnancies, within high-income countries. Methods: We will identify published CPGs addressing any aspect of antenatal management of care in DCDA twin pregnancies, appraise the quality of the identified CPGs using the Appraisal of Guidelines for Research and Evaluation version 2 (AGREE II) the Appraisal of Guidelines Research and Evaluation - Recommendations excellence (AGREE-REX) instruments and examining the recommendations from the identified CPGs. Ultimately, this protocol aspires to clearly define the process for a reproducible systematic review of CPGs within a high-income country, addressing any aspect of antenatal management of DCDA twin pregnancies. PROSPERO registration: CRD42021248586 (24/06/2021).

OBJECTIVE: Twin pregnancies are at increased risk of preterm birth (PTB) compared to singletons. Evaluation of cervical length (CL) represents the optimal tool to screen PTB in singleton. Conversely, there is less evidence on the use of CL in twins. Our aim was to evaluate the methodological quality and clinical heterogeneity of clinical practice guidelines (CPGs) on the CL application in twins using AGREE II methodology.
METHODS: MEDLINE, Scopus, and websites of the main scientific societies were examined. The following aspects were evaluated: diagnostic accuracy of CL, optimal gestational age at assessment and interventions in twin pregnancies with reduced CL. The quality of the published CPGs was carried out using \"The Appraisal of Guidelines for REsearch and Evaluation (AGREE II)\" tool. The quality of guideline was rated using a scoring system. Each considered item was evaluated by the reviewers on a seven-point scale that ranges from 1 (strongly disagree) to 7 (strongly agree). A cut-off >60 % identifies a CPGs as recommended.
RESULTS: The AGREE II standardized domain scores for the first overall assessment had a mean of 74 %. The score was more than 60 % in the 66.6 % of CPGs analyzed indicating an agreement between the reviewers on recommending the use of these CPGs. A significant heterogeneity was found; there was no specific recommendation on CL assessment in about half of the published CPGs. There was also significant heterogeneity on the CL cut-off to prompt intervention.
CONCLUSIONS: Despite the fact that the AGREE II analysis showed that the majority of the included guidelines are of good quality, there was a significant heterogeneity among CPGs as regard as the indication, timing, and cut-off of CL in twins as well as in the indication of interventions.

OBJECTIVE: This review aimed to identify guidelines with recommendations applicable to the antenatal management of dichorionic diamniotic twin pregnancies within high-income countries, appraise their methodological quality, and discuss the similarities and variability across guidelines.
METHODS: A systematic literature review of electronic databases was performed. Manual searches of guideline repositories and websites of professional organisations were performed to identify additional guidelines. The protocol for this systematic review was registered on PROSPERO (CRD42021248586, 25 June 2021). AGREE II and AGREE-REX tools were applied to assess the quality of eligible guidelines. A narrative and thematic synthesis described and compared the guidelines and their recommendations.
RESULTS: Twenty-four guidelines were included, from which 483 recommendations were identified across 4 international organisations and 12 countries. Guidelines addressed eight themes and recommendations were classified accordingly: chorionicity and dating (103 recommendations), fetal growth (105 recommendations), termination of pregnancy (12 recommendations), fetal death (13 recommendations), fetal anomalies (65 recommendations), antenatal care (65 recommendations), preterm labour (56 recommendations) and birth (54 recommendations). Guidelines showed significant variability in recommendations, with conflicting recommendations regarding non-invasive preterm testing, definitions surrounding selective fetal growth restriction, screening for preterm labour and the timing of birth. Guidelines lacked a focus on standard antenatal management of DCDA twins, management of discordant fetal anomaly and single fetal demise.
CONCLUSIONS: Specific guidance for dichorionic diamniotic twins is overall indistinct and access to guidance regarding the antenatal management of these pregnancies is currently difficult. Management of discordant fetal anomaly or single fetal demise needs greater consideration.

Appropriate gestational weight gain (GWG) is essential for maternal and fetal health. For twin pregnancies among Caucasian women, the Institute of Medicine (IOM) guidelines can be used to monitor and guide GWG. We aimed to externally validate and compare the IOM guidelines and the recently released guidelines for Chinese women with twin pregnancies regarding the applicability of their recommendations on total GWG (TGWG).
A retrospective cohort study of 1534 women who were aged 18-45 years and gave birth to twins at ≥ 26 gestational weeks between October 2016 and June 2020 was conducted in Guangzhou, China. Women\'s TGWG was categorized into inadequate, optimal, and excess per the IOM and the Chinese guidelines. Multivariable generalized estimating equations logistic regression was used to estimate the risk associations between TGWG categories and adverse neonatal outcomes. Cohen\'s Kappa coefficient was calculated to evaluate the agreement between the IOM and the Chinese guidelines.
Defined by either the IOM or the Chinese guidelines, women with inadequate TGWG, compared with those with optimal TGWG, demonstrated higher risks of small-for-gestational-age birth and neonatal jaundice, while women with excess TGWG had a higher risk of delivering large-for-gestational-age infants. The agreement between the two guidelines was relatively high (Kappa coefficient = 0.721). Compared with those in the optimal TGWG group by both sets of the guidelines, women classified into the optimal group by the Chinese guidelines but into the inadequate group by the IOM guidelines (n = 214) demonstrated a statistically non-significant increase in the risk of all the adverse neonatal outcomes combined.
The IOM and the Chinese guidelines are both applicable to Chinese women with twin pregnancies.

The applicability of the Institute of Medicine (IOM) recommendations of gestational weight gain (GWG) for Chinese twin gestations is uncertain. In this article, we aimed to investigate the associations between GWG among twin gestations, as categorized according to the 2009 IOM guidelines and perinatal outcomes in Chengdu, China. A retrospective cohort study of pregnant women delivering live twins ≥28 weeks at a tertiary maternal and child hospital was conducted. The incidences of perinatal outcomes were compared across 3 groups-that is, women with low, adequate, and excessive GWG. Logistic regression analyses were next performed to confirm the associations while taking into account potential confounders. Results showed that low GWG was associated with a higher risk of preterm birth, low and very low birthweight, neonatal intensive care unit admission, and gestational diabetes, whereas preeclampsia was more frequent among excessive GWG women. In conclusion, adherence to the 2009 IOM guidelines for twin pregnancies are associated with improved perinatal outcomes. This has the potential to improve short- and long-term public health outcomes.

Objective The objective is to estimate the impact of maternal weight gain outside the 2009 Institute of Medicine recommendations on perinatal outcomes in twin pregnancies. Study Design Twin pregnancies with two live births between January 1, 2004 and December 31, 2014 delivered after 23 weeks Finger Lakes Region Perinatal Data System (FLRPDS) and Central New York Region Perinatal Data System were included. Women were classified into three groups using pre-pregnancy body mass index (BMI). Perinatal outcomes in women with low or excessive weekly maternal weight gain were assessed using normal weekly weight gain as the referent in each BMI group. Results Low weight gain increased the risk of preterm delivery, birth weight less than the 10th percentile for one or both twins and decreased risk of macrosomia across all BMI groups. There was a decreased risk of hypertensive disorders in women with normal pre-pregnancy weight and an increased risk of gestational diabetes with low weight gain in obese women. Excessive weight gain increased the risk of hypertensive disorders and macrosomia across all BMI groups and decreased the risk of birth weight less than 10th percentile one twin in normal pre-pregnancy BMI group. Conclusion Among twin pregnancies, low weight gain is associated with low birth weight and preterm delivery in all BMI groups and increased risk of gestational diabetes in obese women. Our study did not reveal any benefit from excessive weekly weight gain with potential harm of an increase in risk of hypertensive disorders of pregnancy. Normal weight gain per 2009 IOM guidelines should be encouraged to improve pregnancy outcome in all pre-pregnancy BMI groups.