Intergenerational transmission of psychiatric disorders: the 1987 Finnish Birth Cohort study.

The causes of mental disorders are multifactorial including genetic and environmental exposures, parental psychopathology being the greatest risk factor for their offspring. We set out to quantify the risk of parental psychiatric morbidity with the incidence of mental disorders among their offspring before the age of 22 years and study the sex- and age-specific associations. The present study utilises the 1987 Finnish Birth Cohort (FBC) data, which is a register-based follow-up of all 60,069 children born in Finland 1987 and followed-up until 2008. Data on psychiatric morbidity are based on inpatient care episodes of parents and both inpatient and outpatient visits of offspring and were collected from the Finnish Hospital Discharge Register which covers all Finnish citizens accessing specialized care. Altogether 7.6% of the cohort members had a parent or both parents treated at psychiatric inpatient care during the follow-up. Parental psychiatric morbidity increased the offspring's risk for psychiatric diagnoses two to threefold versus those children without parental psychiatric hospitalization, mother's morbidity comprising a greater risk than that of father's. The risk was prominent for both sexes of the offspring throughout childhood and adolescence. Psychiatric disorders possess significant intergenerational continuum. It is essential to target preventive efforts on the high-risk population that comprises families with a parent or both having mental disorders. It also implies developing appropriate social and health care interventions to support the whole family.

Association between parental hospital-treated somatic illnesses in childhood and later mental disorders among offspring up to early adulthood: An explorative study in the 1987 Finnish Birth Cohort.

Aims: Earlier studies on the associations between parental somatic illnesses and children's psychological wellbeing have focused on the most common somatic illnesses or on specific groups of illnesses. In this study, we aimed to systematically examine whether parental somatic illnesses, diagnosed during an offspring's childhood, are associated with later mental disorders of the offspring and, if so, identify which parental somatic illnesses in particular increase the likelihood for later mental disorders among the offspring. Methods: The 1987 Finnish Birth Cohort study yields longitudinal nationwide follow-up data that include a complete census of children born in a single year. Children have been followed over time through to the year 2012 using official registers maintained by the Finnish authorities. Parental diagnoses of specialised hospital inpatient care were identified from the Hospital Discharge Register after children's birth and followed up until the end of 1995. Children's psychiatric diagnoses from specialised hospital care were identified from the same register for the periods 1996/1998-2012. Logistic regression analyses were used to calculate sex-specific odds ratios for associations of mental disorders with maternal and paternal somatic illnesses using parental death, education, social assistance and psychiatric inpatient care as covariates. Results: Parental somatic illnesses during an offspring's childhood seem to increase the risk for later mental disorders. Several previously unreported somatic parental illnesses were found to be significantly associated with offspring's later mental health. Conclusions: Parental somatic illnesses should be considered as a significant adverse childhood life event, calling for preventive actions and child-centred support in adult healthcare.

Pathways from parental mental disorders to offspring's work disability due to depressive or anxiety disorders in early adulthood-The 1987 Finnish Birth Cohort.

BACKGROUND: Parental mental disorders have been shown to predict offspring's mental health problems. We examined whether pathways from parental mental disorders to offspring's psychiatric work disability in early adulthood are mediated through offspring's mental disorders and social disadvantage in adolescence. METHODS: Study population consisted of the 1987 Finnish Birth Cohort. Data on parents' psychiatric care or work disability due to mental diagnosis between 1987 and 2000 and the cohort participants' health and social factors between 2001 and 2005 were derived from administrative national registers. From 2006 through 2015, 52,182 cohort participants were followed for admittance of psychiatric work disability due to depressive or anxiety disorders. First, we applied a pathway analysis to examine the occurrence of each path. We then used mediation analysis to assess the proportion of association between parental mental disorders and work disability mediated by offspring's health and social disadvantage. RESULTS: The pathway model indicated that the association from parental mental disorders to offspring's work disability due to depressive or anxiety disorder is through mental disorders and social disadvantage in adolescence. Odds Ratio for the total effect of parental mental disorders on offspring's psychiatric work disability was 1.85 (95% confidence interval [CI] 1.46-2.34) in the model including offspring's mental disorders that mediated this association by 35%. Corresponding results were 1.86 (95% CI 1.47-2.35) and 28% for social disadvantage in adolescence. CONCLUSIONS: These findings suggest that intergenerational determination of work disability due to mental disorders could be addressed by actions supporting mental health and social circumstances in adolescence.

Evaluation of HPV type-replacement in unvaccinated and vaccinated adolescent females-Post-hoc analysis of a community-randomized clinical trial (II).

Efficacy of human papillomavirus (HPV) vaccines promises to control HPV infections. However, HPV vaccination programs may lay bare an ecological niche for non-vaccine HPV types. We evaluated type-replacement by HPV type and vaccination strategy in a community-randomized trial executed in HPV vaccination naïve population. Thirty-three communities were randomized to gender-neutral vaccination with AS04-adjuvanted HPV16/18 vaccine (Arm A), HPV vaccination of girls and hepatitis B-virus (HBV) vaccination of boys (Arm B) and gender-neutral HBV vaccination (Arm C). Resident 1992-95 born boys (40,852) and girls (39,420) were invited. 11,662 boys and 20,513 girls were vaccinated with 20-30% and 45-48% coverage, respectively. HPV typing of 11,396 cervicovaginal samples was performed by high throughput PCR. Prevalence ratios (PR) between arms and ranked order of HPV types and odds ratio (OR) for having multiple HPV types in HPV16 or 18/45 positive individuals were calculated. The ranked order of HPV types did not significantly differ between arms or birth cohorts. For the non-HPV vaccinated 1992-1993 birth cohorts increased PR, between the gender-neutral intervention versus control arms for HPV39 (PRA 1.84, 95% CI 1.12-3.02) and HPV51 (PRA 1.56, 95% CI 1.11-2.19) were observed. In the gender-neutral arm, increased clustering between HPV39 and the vaccine-covered HPV types 16 or 18/45 (ORA16 = 5.1, ORA18/45 = 11.4) was observed in the non-HPV vaccinated 1994-1995 birth cohorts. Comparable clustering was seen between HPV51 and HPV16 or HPV18/45 (ORB16 = 4.7, ORB18/45 = 4.3), in the girls-only arm. In conclusion, definitively consistent postvaccination patterns of HPV type-replacement were not observed. Future occurrence of HPV39 and HPV51 warrant investigation.

Parental hospital-treated somatic illnesses during offspring's childhood associated with later offspring use of psychotropic medication during childhood to young adult - The 1987 Finnish Birth Cohort study.

This study aimed to systematically examine whether parental hospital-treated somatic illnesses, diagnosed during an offspring's childhood (1987-1995), are associated with later use of psychotropic medication (1996-2012) by the offspring. If so, which parental somatic illnesses, in particular, increase the likelihood for later use of psychotropic medication among the offspring. The 1987 Finnish Birth Cohort study yields longitudinal nationwide follow-up data that include a complete census of children born in a single year. A total 58,551 offspring are included in this study and, of these 57,752 had a known father. Offspring who had used psychotropic medication between the ages of 9 and 24 years, more often had parents who had experienced a greater number of somatic illnesses when their child was aged under 9, compared to offspring without any use of psychotropic medication. The specific parental somatic illnesses early in life, for example disorders of female tract (OR 1.12, 95%CI 1.01-1.23), pregnancy with abortive outcome (1.18, 1.09-1.28), paternal acute infections (1.20, 1.05-1.38), and paternal symptoms, signs, and ill-defined conditions (1.21, 1.03-1.42), were found to be associated with psychotropic medication treatment using parental-related determinants; death, education, receipt of social assistance and psychiatric inpatient care as covariates. This suggests that these specific parental somatic illnesses can affect psychological well-being of the offspring. Preventive actions and support for the child, should be provided in situations where a parent with a somatic illness has limited ability to care for and rear their child.

Psychiatric diagnoses of children affected by their parents' traumatic brain injury: the 1987 Finnish Birth Cohort study.

OBJECTIVE: To investigate whether parental TBI increases the overall risk for psychiatric disorders and the risk for specific psychiatric diagnoses in the children affected by parental TBI. METHODS: The 1987 Finnish Birth Cohort (n = 59 476) were followed up through national registers from birth to the end of 2008. The diagnoses of cohort members and their parents were obtained from the Care Register of Health Care, provided by the National Institute of Health and Welfare. RESULTS: During the 21-year follow-up, the likelihood for psychiatric diagnoses being assessed in psychiatric care was significantly increased in males with any mental disorder (odds ratio (OR) = 1.43), substance-use-related disorders (OR = 1.71) and behavioural and emotional disorders (OR = 1.75), and in females with disorders of psychological development (OR = 1.85). CONCLUSIONS: Children affected by parental TBI are at increased risk for psychiatric disorders: males for externalizing disorders and females for developmental disorders. Observed gender interactions in the association between parental TBI and the psychiatric disorders of children warrant further study.

Mental disorder diagnoses of offspring affected by parental cancer before early adulthood: the 1987 Finnish Birth Cohort study.

OBJECTIVE: The purpose of this study is to investigate psychiatric diagnoses given to children affected by parental cancer in psychiatric and somatic specialized health care settings. METHODS: The 1987 Finnish Birth Cohort data (n = 59 476) were followed up through national registers from birth of cohort members up to the end of 2008. The health-related data of cohort members and their parents were obtained from the Care Register of Health Care provided by the National Institute of Health and Wellbeing. RESULTS: By the age of 21 years 7711 of the cohort members had used specialized psychiatric outpatient care and, of them, 549 (7.1%) were affected by parental cancer. Of affected offspring a mental disorder diagnosis was made in 424 (77.2%), while 125 (22.8%) children had not been given any specific mental disorder diagnosis. In females the likelihood for a mental disorder diagnosis assessed in outpatient care was significantly increased by up to 1.2 fold in cases of parental cancer. In males with a father having cancer, psychological development disorders were significantly increased whether assessed in outpatient (OR 1.5) or inpatient (OR1.9) settings. CONCLUSIONS: The prevalence of psychiatric diagnoses in children with parental cancer does not seem to differ from those of children with parents without cancer. However, evidence was found that children affected by parental cancer are at increased risk for some specific psychiatric disorders. Quarter of affected offspring who were referred to specialized psychiatric outpatient care only received diagnoses related to use of health care services or crises or received no psychiatric diagnosis at all. Copyright © 2016 John Wiley & Sons, Ltd.

Determinants of underage induced abortion--the 1987 Finnish Birth Cohort study.

INTRODUCTION: Although underage pregnancies often end in induced abortion, data on girls who undergo termination of pregnancy are lacking. Our aim was to identify determinants of underage induced abortion and compare them with those of childbirth. MATERIAL AND METHODS: All girls born in 1987 in Finland surviving the perinatal period (n = 29 041) were included in the study and divided into three study groups: Girls undergoing induced abortion (n = 1041, 3.6%) or childbirth (n = 395, 1.4%) at <18 years of age and girls with no underage pregnancies (n = 27 605, 95.0%). RESULTS: Shared risk factors of underage induced abortion and childbirth included early onset behavioral and emotional disorders [adjusted OR 1.9 (1.4-2.5) and 2.7 (95% CI 1.8-3.9)], a history of foster care [1.5 [1.1-1.9] and 3.0 [2.3-4.1)], and socioeconomic factors, including living in a family receiving income support [1.8 (1.5-2.1) and 3.4 (2.7-4.4)], respectively. Specific risk factors of underage induced abortion were psychoactive substance use disorders [2.2 (1.3-3.5)], having a mother who smoked during pregnancy [1.5 (1.3-1.8)] or had undergone induced abortion [1.8 (1.5-2.2)]. Coping with a chronic physical illness [0.7 (0.5-0.9)], and perinatal problems [0.6 (0.4-0.7)] were inversely associated with underage induced abortion. CONCLUSIONS: The traditionally acknowledged determinants of underage childbirth played a less prominent role in induced abortion. Novel risk factors of underage induced abortion were found, including severe substance abuse and adverse maternal reproductive history, and should be addressed at all levels offering youth healthcare and social welfare services.

Changes over time in the Chlamydia trachomatis serotype distribution in Finnish women.

The distribution of Chlamydia trachomatis serotypes in the sexually active population may change over time. Serum from C. trachomatis seropositive women representing the 1980s, 1990s, and 2000s were available from a stratified random sample (11,067) of the Finnish Maternity Cohort for microimmunofluorescence-based classification. The C. trachomatis serotype distributions in the 1980s and 2000s were comparable, with serotypes G, E, and J being the most prevalent. In the 1990s the numbers of women seropositive for ≥ 2 serotypes peaked, and serotypes G/J were replaced by serotypes E/D. The temporary C. trachomatis serotype replacement parallels changes in the sexually active population in the 1990s in Finland.

Order of HPV/Chlamydia infections and cervical high-grade precancer risk: a case-cohort study.

Interactions of carcinogenic human papillomaviruses (most notably HPV types 16/18/31/33/45), and HPV6 or Chlamydia trachomatis are not well understood. We have used seroconversions to study effects the order of these infections has on the risk of high-grade cervical precancer. In a cohort of 94,349 Finnish women with paired sera from consecutive pregnancies within an average of 2.4 years, 490 were diagnosed with cervical CIN3/AIS. Serum antibodies to HPV6/16/18/31/33/45 and C. trachomatis were measured in paired sera of the cases and a subcohort of 2,796 women with a minimum of two pregnancies. HPV16-adjusted rate ratios (RR) and confidence intervals were estimated by stratified Cox model. Compared to dual seropositivity already at the first serum sampling, RRs related to HPV6 seropositivity before and after HPV31 seroconversion were 0.4 (95% CI 0.0, 4.4) and 10 (95% CI 1.8, 57). Furthermore, RR related to seroconversions of both HPV18/45 and C.trachomatis between the consecutive pregnancies was 28 (95% CI 4.3, 190). Virtually concomitant HPV18/45 and C.trachomatis infections are associated with very high CIN3 risk.

Socioeconomic and regional aspects in the use of specialized psychiatric care--a Finnish nationwide follow-up study.

BACKGROUND: Mental health problems in childhood and adolescence are an important public health concern. The general aim of Finnish health policy is to offer equal services for all inhabitants according to need, irrespective of socio-economic background or place of residence. Here, we assess equity in access to psychiatric care in a long-term nationwide follow-up study from birth to early adulthood. METHODS: All 60 069 children born in Finland in 1987 were followed up through health registers from 1987 to 2008. The cohort members' use of specialized psychiatric outpatient and inpatient care was assessed and linked to their socio-economic status and residential area. RESULTS: Altogether, 14.4% of the cohort members had received specialized psychiatric care during the follow-up. Females used significantly more specialized psychiatric outpatient care than males. In addition, the use of specialized psychiatric care was more common among young people with a poor socio-economic background and those living in urban areas. CONCLUSIONS: A notable number of the young adults born in Finland in 1987 used specialized psychiatric care during their childhood and adolescence. Use was clearly defined by sex and residential area, as well as by parental socio-economic status and education. The data indicate that equity in access to mental health services should be highlighted in health policies, as contemporary outpatient mental health care has not been equally available for people living within and outside urban areas.

The "Let's Talk about Children" intervention in a Finnish school context: fidelity, parents' experiences, and perceived benefits.

The Let's Talk about Children intervention is a tool for parents and professionals to work together to promote children's positive development, resilience, and psychosocial well-being in social and healthcare services, at school, and in day care. The aim of this study was to evaluate the fidelity, parents' experiences, and perceived benefits of using the Let's Talk about Children intervention in a school context. Participants (N = 65 first-grader parents) completed an online questionnaire after the intervention. The results show that the intervention was delivered as designed and conducted with high fidelity. Parents' experiences of the Let's Talk about Children discussions were positive, parents felt that the atmosphere was good during the discussion, and the participants reported benefits from the intervention. Clinical trial registration:ClinicalTrials.gov, identifier NCT05038280.

The prevalence of children affected by parental cancer and their use of specialized psychiatric services: the 1987 Finnish Birth Cohort study.

The studies reporting population-based estimates of the proportion of children with a parent suffering from cancer are very few. These children have been shown to suffer from psychological symptoms, but it is not known whether their use of psychiatric services is increased. Our study examined the prevalence of children affected by parental cancer at national level and whether these children use specialized psychiatric services more than their peers. The study is a retrospective population-based registry study. All 60,069 children born in Finland in 1987 were followed up with various health and social registers from 1987 to 2008. The associations of parental cancer treatments with children's psychiatric service use were analyzed with logistic regressions. During the 21-year follow-up 3,909 (6.6%) of the children had a parent suffering from cancer. The children of the cancer patients used more specialized psychiatric care than their peers and the service use depended on parent's gender, as well as cohort members' gender and the age at occurrence. The combination of parental cancer and psychiatric disorder, whether the ill parent or spouse, increased the children's psychiatric service use even more. Children affected by parental cancer comprise a substantial part of the population in society using increased level of psychiatric services. Parental cancer is clearly an illness which has to be taken into account in planning child- and parenting-focused prevention and promotion actions in adult health care. "Parent's cancer is like a tsunami which rolls over the whole family. If it struck a thousand families at the same time the whole healthcare system would be mobilized. But when it strikes one family at a time you are left alone with your children" (quote from a father during a family intervention). Weaver et al.1 have reported that 14% of all cancer survivors in the USA have minor dependent children, representing a population of about 1.58 million survivors and 2.85 million children. A significant part of working age population is thus struggling with concerns related to serious illness, parenting and the wellbeing of children.

Occurrence of vaccine and non-vaccine human papillomavirus types in adolescent Finnish females 4 years post-vaccination.

Control of human papillomavirus (HPV)-related cancers by inclusion of HPV vaccination into national vaccination programmes is likely. One open question is replacement of the vaccine types with other high-risk (hr) HPV types in the vaccination era. We studied occurrence of HPV types in adolescent females participating in a population-based vaccination trial. A total of 4,808 16- to 17-year-old females from Finland were enrolled in the 1:1 randomized phase III (PATRICIA) trial of the efficacy of vaccination with the AS04-adjuvanted HPV-16/18 virus-like particle vaccine as compared to hepatitis A virus (HAV) vaccine. HPV infection was assessed from cervical samples taken every 6 months for 4 years post-vaccination by polymerase chain reaction (PCR) for genital oncogenic HPV types 16, 18, 31, 33, 35, 39, 45, 51, 52, 58, 59, 66, 68, and 73 as well as low-risk types HPV-6 and HPV-11. The HPV-16/18 vaccine coverage ranged between 1 and 22% by age-cohort and study community. Odds ratios (ORs) for infections with different HPV types in baseline PCR negative HPV-16/18 vs. HAV vaccinated women, and Poisson regression derived HPV incidence rate ratios (IRRs) in baseline positive vs. negative women were calculated. The OR and IRR estimates for acquisition of any genital HPV types showed no excess risk neither in baseline HPV DNA-negative HPV-16/18-vaccinated women compared to baseline HPV DNA-negative HAV vaccinated women nor in HPV-16/18-vaccinated baseline HPV-16/18-positive women compared to baseline HPV-16/18-negative women. In the HAV-vaccinated, baseline HPV-18-positive women showed an increased risk of acquiring other clade A7 HPV types (39, 45, 59, 68) (IRR 1.8, 95% confidence interval = 1.01.-3.1). We found no increased occurrence of non-vaccine HPV types suggestive of type-replacement 1-4 years post-vaccination among HPV-16/18-vaccinated Finnish adolescents.

The effect of birth order on length of hospitalization for pediatric traumatic brain injury: an analysis of the 1987 Finnish birth cohort.

PURPOSE: This study examines the relationship between birth order and length of hospitalization due to pediatric traumatic brain injury (TBI). METHODS: We prospectively followed 59,469 Finnish newborns from 1987 until age 18 years. Data on first diagnosis of TBI was recorded within the 1987 Finnish Birth Cohort (FBC). Hospitalization period was divided into two categories: 2 days or less and more than 2 days. The latter was considered in this study as longer hospitalization. RESULTS: Compared with first born siblings, later born siblings had an increased risk of a longer hospitalization for TBI (12.7% of fourth or higher born birth children diagnosed with TBI were hospitalized for 2 or more days, 11.3% of first born, 10.4% of third born and 9.0% of second born). Fourth or higher born children were more likely to experience a repeat TBI; 13.4% of fourth or higher born children diagnosed with TBI had 2-3 TBIs during the study period compared to 9% of third born, 7.8% of second born and 8.8% of the first born. Injuries in the traffic environment and falls were the most common contributors to pediatric TBI and occurred most frequently in the fourth or higher birth category; 29.3% of TBIs among fourth or higher birth order were due to transport accidents and 21% were due to falls. CONCLUSIONS: This study revealed a significant increase in risk for longer hospitalization due to TBI among later born children within the same sibling group. The study provides epidemiological evidence on birth order as it relates to TBI, and its potential to help to explain some of the statistical variability in pediatric TBI hospitalization over time in this population.

Parent Support Programmes for Families Who are Immigrants: A Scoping Review.

Parental support is of paramount importance in the promotion of positive parenting, strengthening parenthood and protecting children from disadvantages due to immigration experiences. The aim was to describe what is known about parent support programmes targeted to families who are immigrants. Electronic databases and the grey literature were systematically and comprehensively searched with no time/language restrictions. JBI approach and PRISMA-ScR were used to guide the review. N = 88 articles were sourced. Interventions were targeted to improve parental practices, skills and family wellbeing, usually through group-based methods. Most interventions included components of positive parenting and family communication. Identifying the needs of the target group and cultural tailoring were reported to be highly important in gaining acceptability, promoting engagement and producing benefits. Parent support programmes for families who are immigrants potentially improve positive parental practices and families' wellbeing. There are many applicable and effective interventions to be exploited.

Birth order and pediatric traumatic brain injury.

Pediatric traumatic brain injury (TBI) is a significant problem of public health importance worldwide. Large population-based studies on the effect of birth order on health phenomena are exceedingly rare. This study examines the relationship between birth order and risk for pediatric TBI among sibling groups. We performed a retrospective cohort study following 59,469 Finnish newborns from 1987 until age 18 years. Data on first diagnosis of TBI was recorded within the 1987 Finnish Birth Cohort (FBC). Compared with first born siblings, later born siblings had an increased risk of TBI during the follow-up period (hazard ratio [HR] 1.02; 95% confidence interval [CI] 0.91-1.14 for second born, HR 1.09; 95% CI 0.95 1.26 for third born, HR 1.28; 95% CI 1.08-1.53 for fourth or higher). When adjusted for sex and maternal age at child's birth, HRs (95% CIs) for TBI during the follow-up period were 1.12 (0.99-1.26) for second born, 1.31 (1.12-1.53) for third born and 1.61 (1.33-1.95) for fourth born or higher children, respectively. Within this large register-based population-wide study, order of birth modified risk for pediatric TBI among sibling groups. Taken together, these study findings may serve to stimulate further inquiry into genetic, psychological, or psychosocial factors which underlie differences in risk and depth of effect within and between sibling groups.

Predicting the stability of early employment with its timing and childhood social and health-related predictors: a mixture Markov model approach.

To extend work careers, it is important to focus on all working-aged people including young adults. The aim of this study was to identify typical patterns of work participation among young adults after their first entry into the labour market and to examine whether the timing of entry together with parental and own socio-economic position and health predict early work participation. More in-depth understanding of early careers and their early determinants is important to plan targeted interventions and to promote more stable work participation among young adults. We used the Finnish Birth Cohort 1987 including data from several registers from all 59,476 children born in 1987 as well as their parents, followed until 2015. We estimated a mixture Markov model that allowed for joint identification of latent classes of labour-market attachment, estimation of labour-market transitions within classes, and prediction of class membership using childhood social and health-related determinants. We observed that the first entry into the labour market as measured by six months in continuous employment was not a permanent entry for many, not only due to negative reasons such as unemployment and ill health but also due to more voluntary reasons such as studies. Individuals entering the labour market at a later age were more likely to be in continuous employment thereafter. More advantaged background predicted exits due to studies or - when following a late entry - stable employment, while disadvantaged background factors predicted more unstable work and long-term exits from the labour market.

Differences in incidence and co-occurrence of vaccine and nonvaccine human papillomavirus types in Finnish population before human papillomavirus mass vaccination suggest competitive advantage for HPV33.

To understand likelihood of type replacement after vaccination against the high-risk human papillomavirus (HPV) types, we evaluated competition of the seven most common genital HPV types in a population sample of unvaccinated, fertile-aged Finnish women. First trimester sera from two consecutive pregnancies were retrieved from 3,183 Finnish women (mean age, 23.1 years) of whom 42.3% had antibodies to at least one HPV type (6/11/16/18/31/33/45) at the baseline. Antibody positivity to more than one HPV types by the second pregnancy was common among the baseline HPV seropositives. However, compared to baseline HPV-seronegative women, significantly increased incidence rate ratios (IRRs), indicating an increased risk to seroconvert for another HPV type, were consistently noted only for HPV33 among baseline HPV16 or HPV18 antibody (ab)-positive women: HPV(16ab only) (→) (16&33ab) IRR 2.9 [95% confidence interval (CI) 1.6-5.4] and HPV(18ab only) (→) (18&33ab) IRR 2.5 (95% CI 1.1-6.0), irrespectively of the presence of antibodies to other HPV types at baseline: HPV(16ab) (→) (16&33ab) IRR 3.2 (95% CI 2.0-5.2) and HPV(18ab) (→) (18&33ab) IRR 3.6 (95% CI 2.1-5.9). Our findings suggest a possible competitive advantage for HPV33 over other genital HPV types in the unvaccinated population. HPV33 should be monitored for type replacement after HPV mass vaccination.