Changes in worry symptoms will be assessed through the Penn State Worry Questionnaire (PSWQ; Meyer et al.,1990) to examine whether CBT for perinatal anxiety is effective in reducing worry. Items on the PSWQ are rated from 1 (not at all typical of me) to 5 (very typical of me), with higher total scores indicating higher levels of worry. Scores on the PSWQ can range from 16 to 80.

Changes in intolerance of uncertainty will be assessed through the Intolerance of Uncertainty Scale (IUS-12; Carleton, R. N., Norton, M. P. J., & Asmundson, G. J, 2007) to examine whether CBT for perinatal anxiety is effective in reducing intolerance of uncertainty. Items on the IUS-12 are rated on a 5-point likert scale ranging from 1 (not at all characteristic of me) to 5 (entirely characteristic of me). Higher scores indicate great levels of intolerance of uncertainty and are associated with worse outcomes. The IUS-12 has a total score, along with two subscale scores. The prospective anxiety subscale comprises of seven items, with possible scores ranging from 7-35. The inhibitory anxiety scale comprises of five items, with possible scores ranging from 5-25. The total IUS-12 score is calculated by summing the two subscales, meaning total scores range from 12-60.

Changes in general perfectionism symptoms will be assessed through the Multidimensional perfectionism scale (MPS; Hewitt et al.,1991) to examine whether CBT for perinatal anxiety is effective in reducing perfectionism. Items on the MPS are rated on a 7-point scale ranging from 1-7. The MPS is comprised of three subscales with 15 items each that measure self-oriented perfectionism, other-oriented perfectionism, and socially prescribed perfectionism. Scores on each subscale range from 15-105, with higher scores indicating greater levels of that type of perfectionism. A total score on the MPS can be obtained by summing the three subscales making the total score range 45-315.

Changes in parenting perfectionism symptoms will be assessed through the Multidimensional parenting perfectionism scale (MPPQ; Snell, 1997) to examine whether CBT for perinatal anxiety is effective in reducing parental perfectionism. Items on the MPPQ are rated on a 5-point scale ranging from 0 (not at all characteristic of me) to 4 (very characteristic of me) , with higher scores indicating greater amounts of parental perfectionism. The MPPQ has 11 subscales. Each subscale has 5-items with scores ranging from 0-20. Total scores are obtained by summing all subscale scores and can range from 0-260.

Changes in parenting competence will be assessed through Parenting Sense of Competence Scale (PSOC; Gibaud-Wallston & Wandersman, 1978) to examine whether CBT for perinatal anxiety is effective in increasing sense of competence. Items on the PSOC are rated from 1 (strongly disagree) to 6 (strongly agree), with total scores on the PSOC ranging from 17-102. Higher total scores on the PSOC indicate a higher sense of parenting competency.

Social support will be assessed through the Social Provisions Scale (SPS; Cutrona & Russell, 1987) to examine whether CBT for perinatal anxiety is effective in increasing the degree to which the participant's social relationships provide dimensions of social support. Items on the SPS are rated on a 4-point scale ranging from 1-4. Total scores on the SPS range from 24-96, with higher scores indicating greater social support.

Changes in relationship satisfaction will be assessed through Abbreviated Dyadic Adjustment Scale (ADAS; Spanier, 1976) to examine whether CBT for perinatal anxiety is effective in increasing the self-reported quality of marital and other close relationships. Items 1-6 on the ADAS are rated on a 6-point scale ranging from 0-5. Item 7 is rated on a 7-point scale ranging from 0 (extremely unhappy) to 6 (perfect) and provides a happiness rating. Item 7 is not included in the total score for the ADAS, meaning total scores can range from 0-30. Higher scores on the ADAS indicate higher levels of adjustment within a relationship with a partner.

Changes in perceived Stress will be assessed through the Perceived Stress Scale (PSS-14; Cohen, 1994) to examine whether CBT for perinatal anxiety is effective in reducing the extent to which situations in life are perceived as stressful. Items on the PSS-14 are rated on a 5-point scale ranging from 0 (never) to 4 (very often), with total scores ranging from 0-56. Higher scores on the PSS-14 indicate greater levels of perceived stress.

Changes in emotion Regulation will be assessed through the Emotion Regulation Questionnaire (ERQ; Gross & John, 20003) and the Difficulties in Emotion Regulation Scale (DERS-II; Gratz & Roemer, 2005) to examine whether CBT for perinatal anxiety has an impact on emotion regulation abilities. Items on the ERQ are rated on a 7-point scale ranging from 1 (strongly disagree) to 7 (strongly agree).The ERQ has two subscales, a Cognitive Reappraisal subscale and an Expressive Suppression subscale. Six items comprise the Cognitive Reappraisal subscale, meaning scores on this subscale range from 6-42. Four items comprise the Expressive Suppression subscale, meaning scores on this subscale range from 4-28.A total score can be obtained by summing the two subscales, meaning the total score range is 10-70. Higher scores indicate greater use of emotion regulation strategies.

Overall difficulties in functioning will be assessed through the World Health Disability Assessment Schedule 2.0 (WHODAS; WHO, 2010) to examine whether CBT for perinatal anxiety is effective in increasing overall level of functioning. Items on the WHODAS are rated by a clinician on a 5-point scale ranging from 1 (none) to 5 (extreme). Total scores range from 0-60, with greater scores indicating greater disability, or worse overall functioning.

The Hamilton Anxiety Scale is an interview format rating scale developed to quantify the severity of anxiety symptomatology and contains a global score (HAM-A; Hamilton, 1956). In the current study, the HAM-A will be used to assess changes in anxiety to examine whether CBT for perinatal anxiety is effective in reducing anxiety symptoms. Items on the HAM-A are scored on a 5-point scale ranging from 0 (not present) to 4 (severe), with a total score range of 0-56. Scores less than 17 indicate mild severity, scores between 18-24 indicate mild to moderate severity and scores between 25-30 indicated moderate to severe anxiety symptoms.

The Montgomery-Asberg Depression Rating Scale (MADRS; Montgomery & Asberg, 1979) is a measure that requires an interview format assessing depressive symptoms and contains a global severity score. Items on the MADRS are rated on a 6-point scale ranging from 0-6, with total scores ranging from 0-48. Higher total scores indicate greater depressive symptoms.

Changes in emotion regulation will be assessed through the Difficulties in Emotion Regulation Scale (DERS-II; Gratz & Roemer, 2005) and the Emotion Regulation Questionnaire (ERQ, Gross & John, 2003) to examine whether CBT for perinatal anxiety has an impact on emotion regulation abilities. The DERS-II is rated on a 5-point scale ranging from 1 (almost never) to 5 (almost always), with total scores ranging from 39-195. The DERS-II has six factors: Lack of Emotional Awareness (6 items, range 6-30), Lack of Emotional Clarity (5 items, range 5-25), Difficulties Controlling Impulsive Behaviours When Distressed (6 items, range 6-30), Difficulties Engaging in Goal-Directed Behaviour When Distressed (5 items, range, 5-25), Nonacceptance of Negative Emotional Responses (6 items, range 6-30), and Limited Access to Effective ER Strategies (8 items, range 8-40). Total scores are a sum of subscale scores and higher total scores indicate more difficulties with emotion regulation.

Changes in anxiety related behaviours (e.g., avoidance and safety behaviours) will be assessed through the Worry Behaviors Inventory (WBI; Mahoney et al., 2016) to examine whether CBT for perinatal anxiety is effective in reducing worry-related behaviours. Items on the WBI are rated on a 5-point scale ranging from 0 (none of the time) to 4 (all of the time), with total scores ranging from 0-40. The WBI has two subscales that measure avoidance (3 items, range 0-12) and safety behaviours (7 items, range 0-28) respectively. Total scores on the WBI are calculated by summing the two subscales. Higher scores indicate greater use of worry related behaviours.

Changes in sexual desire, lubrication, orgasm propensity, satisfaction, and pain will be assessed using The Female Sexual Function Index (FSFI; Rosen et al., 2010) to examine whether CBT for perinatal anxiety has an impact on these areas of sexual function. Items one and two on the FSFI are rated on a 5-point scale ranging from 1-5, while items 3-19 are rated on a six-point scale ranging from 0-5. Total scores on the FSFI are obtained by adding the six domain scores together, and range from 2-36. Higher scores on the FSFI indicate lower sexual functioning.

Changes in sexual quality of life will be assessed using The Sexual Quality of Life - Female (SQoL-F; Symonds et al., 2005) to examine whether CBT for perinatal anxiety has in impact on female sexual dysfunction and women's quality of life. Items on the SQoL-F are scored on a 6-point scale ranging from 1 (completely disagree) to 6 (completely agree). Total scores range from 18-108, with higher scores indicating better female sexual quality of life.

Satisfaction of participants receiving CBT for perinatal anxiety will be assessed using the Client Satisfaction Questionnaire (CSQ; Larsen et al., 1979) to examine whether participants are satisfied with the services they have received. Items on the CSQ are rated on a 4-point scale ranging from 1-4. Total scores on the CSQ are a sum ranging from 8-32, with higher scores indicating greater satisfaction with the services received.

Mother-infant bonding will be assessed using the Postpartum Bonding Questionnaire (PBQ; Brockington et al., 2001) to examine whether CBT for perinatal anxiety has an impact on bonding. Items on the PBQ are rated on a 6-point scale ranging from 0 (never) to 5 (always). Total scores on the PBQ range from 0-125. Higher scores on this measure indicate problematic mother-infant bonding.