How safe are breast implants?

September 25, 2018

Women with silicone breast implants may be at increased risk for several rare adverse events, according to the first comprehensive study of long-term outcomes since the implants were reapproved. PLUS: Does delayed childbearing contribute to rates of multiple birth? ALSO: Does prenatal pollution exposure impact a newborn’s thyroid function?

Women with silicone breast implants may be at increased risk for several rare adverse events, according to the first comprehensive study of long-term outcomes since the implants were reapproved. The findings-and an editorial from the US Food and Drug Administration expressing concerns about the controversial data-were  published in Annals of Surgery. 

In the early 1990s, the FDA prohibited use of silicone breast implants following public concerns about health risks. However, subsequent research found no link between implants and the cited diseases. In 2006, the FDA approved sales of silicone implant by two manufacturers-Allergan and Mentor Corp-with the stipulation that they both conduct large post-approval studies (LPAS) to monitor long-term health and safety outcomes. 

The LPAS included 99,903 total patients; Allergan enrolled 41,342 patients with silicone implants and 15,646 with saline and Mentor enrolled 41,975 patients with silicone and 1030 with saline. The majority of patients received silicone implants for primary augmentation (56%). The primary outcome of the research was rare harm, including cumulative trauma disorder (CTD), neurological, autoimmune disease, cancer, self-harm/wellbeing/satisfaction, and reproduction. Secondary outcomes included imaging surveillance, local complications and reoperation. 

The authors found that women who had silicone breast implants were at increased risk of several harms compared to the general public. Using standardized incidence ratios (SIR), women with silicone were found to be approximately eight times more likely to be diagnosed with Sjogren’s syndrome (SIR: 8.14, 95% CI 6.24-10.44), < 0.001); seven times likelier to be diagnosed with scleroderma (SIR: 7.00, 95% CI 5.12-9.34, P< 0.001); and almost six times likelier to be diagnosed with rheumatoid arthritis (SIR: 5.96, 95% CI: 5.35-6.62, P<0.001). 

Women with the implants were also at a higher risk for melanoma (SIR: 3.71, 95% CI 2.87-4.73, P< 0.001). In terms of reproduction, women with silicone implants did not have a significantly higher risk for miscarriage but they were at higher risk for stillbirth (SIR: 4.50, 95% CI 3.59-5.56, < 0.001). Unlike in previous studies, the authors did not find an increased risk of suicide among women with silicone implants.

When the authors compared silicone and saline implants, they found that silicone was linked to a higher risk of surgical complications. These included an increased risk of capsular contracture for silicone compared to saline (5.0% versus 2.8%, respectively) and higher rates of short-term reoperation for silicone (6.5% versus 3.4% at 2 years, respectively). 

While certain harms and adverse outcomes appear to be more frequent with silicone implants, the authors noted several limitations to the study and emphasized that the results are inconclusive as a result. In the editorial, the FDA said, the researchers “failed to account for methodologic differences between studies, inconsistencies in the data, differential loss to follow-up, confounding and other potential sources of bias.” Noting that “the report’s conclusions should be viewed with caution,” the agency said that a public meeting of its Medical Devices Advisory Committee will be held in 2019 to promote public dialogue and discussion about currently available scientific information on breast implants. 

Does delayed childbearing contribute to rates of multiple birth?

Pregnancy in women aged 35 year increased nine-fold between 1972 and 2012. As this shift occurred, plural birth also increased, prompting researchers to look for connections between the two trends. Results of a study in Obstetrics and Gynecologyhelp quantify the contribution of delayed childbearing to the national plural birth excess.

Using data reported by the National Center for Health Statistics, the authors estimated the contribution of delayed childbearing to the national plural birth excess through 2016. They compared the national birth cohort’s plural birth rates before use of assisted reproductive technology (ART) with those after ART emerged. 

Before ART (1949 to 1966), the national birth cohort (n=71,570,717) consisted of 1.4 million twin and more than 19,000 higher-order plural births. Between 1971-2016, the era during which ART emerged, the national birth cohort (n=166,817,655), consisted of 4.3 million twin and nearly 175,000 higher-order plural births. White and black maternal race categories accounted for 99% or the total national birth complement between 1949 and 1966.  Between 1971 and2016, the white and black race categories accounted for 89% of the annual total birth complement.

Relative risk estimates of unassisted plural births by maternal age before the ART era (1949-1966) were unimodal and race-dependent. For black women aged 35 to 39, risk of unassisted plural births was 2.75-fold higher than their 15- to 19-year-old counterparts (39.81/1,000 births to 14.48/1,000 births; 95% CI 2.67-2.83). In comparably aged white women, a 2.47-fold risk increment was found (28.76/1,000 births to 11.63/1,000 births; 95% CI 2.43-2.52). 

The authors noted a rising trend of unassisted plural births during the latter era in both white and black women. White women had 255,964 (95% CI 134,746-375,581) unassisted plural births during this period versus 66,271 (95% CI 34,099-96,197) in black women. In 2016 alone, delayed childbearing accounted for 24% (95% CI 28-47%) of the national plural birth excess for white women and 38% (95% CI 28-47%) for black women. 

The authors also included a simulated projection through 2025 (with the assumption that trends observed through 2016 will continue apace), and concluded that delayed childbearing could account for as much as 46% (95% CI 28-47%) of unassisted plural births for white women and as much as 40% (95% CI 30-53%) for black women. 

The authors note a few strengths and limitations of their study. Among the identified strengths were the reliance on large birth cohorts and use of time intervals preceding and coinciding with the ART era. Limitations included absence of variables other than age and race, absence of family history, and the unfeasibility of correcting for coincident decrements in perinatal and maternal mortality resulting from healthcare improvements. 

The researchers also noted that their 2025 projections assumed that current trends will persist through the next decade and could be erroneous. While the authors acknowledged that more in-depth research is necessary, their findings, they said, indicate that delayed pregnancy has a role in the plural birth excess and ob/gyns and their patients should be aware of the effects when discussing family planning decisions. 

Does prenatal pollution exposure impact a newborn’s thyroid function?

Environmental pollutants are known to be associated with altered thyroid function in newborns. Infants also may be adversely affected by air pollution from particulate matter (PM)-and one of the keys may be a critical window of exposure during pregnancy, according to new research.

Published in JAMA Network Open, the findings are from a cohort study supported by the National Institutes of Health based on data from the Children’s Health Study. The authors looked at the association of prenatal exposure to ambient and traffic-related air pollutants and newborn thyroid functionand prenatal exposures. 

The 2050 participants were recruited from schools in 13 southern California communities in 2002 to 2003 when they were aged 5 to 7 years. Pregnancy and birth data were from 1994 to 1997. All of the children could be linked to their newborn blood spot and complete monthly exposure measures were available for them for at least one air pollutant across their mother’s pregnancy.

The investigators used inverse distance-squared weighting of central monitoring data and the California Line Source Dispersion model (CALINE4), respectively, to determine prenatal monthly averages for ambient and traffic-related (freeway, nonfreeway, and total nitrogen oxides) air pollution exposures.  (CALINE4 predicts air pollutant concentrations near roadways.) Retrospective data from the participants’ newborn heel-stick blood spot total thyroxine (TT4) measures were provided retrospectively by the California Department of Public Health.

Of the newborns, half were male and more than half were Hispanic white (50.5% and 58.6%, respectively); 66 (3.2%) were black and 144 (7.0%) were from other racial/ethnic groups. Variables assessed by the investigators included maternal and paternal tobacco use during pregnancy, maternal education, newborn sex, and total household income.  

The mean (SD) newborn TT4 measure was 16.2 (4.3) µg/dL. A 2-SD increase in prenatal exposure to pollutants that were ambient and small (diameter < 2.5 µm) or larger (diameter < 10 µm) was associated with 1.2-µg/dL and 1.5- µg/dL higher TT4 measures, respectively in covariate-adjusted linear regression models. Other pollutants were not consistently associated with newborn TT4. 

Distributed lag models showed that exposure to the smaller ambient pollutants during months 3 to 7 of pregnancy and to the larger particles during months 1 to 8 of pregnancy were associated with significantly higher newborn TT4 concentrations (P< .05). The strongest association between the smallest ambient pollutants and thyroid function was seen during month 5 of pregnancy versus month 1 for the association between the larger air pollutants and TT4. No significant interactions were observed between any of the pollutants and maternal smoking, newborn sex, birth weight, gestational age at birth, or season of birth.    

The authors said theirs was only the second study to look at associations between ambient PM air pollution exposure and newborn thyroid function. They theorize that midpregnancy may be a particularly vulnerable time for the interaction because that is when the fetus starts producing its own supply of T4. They noted that only TT4 measures were available for most of the participants and that no information was available on maternal thyroid function. Strengths of the study included the capture of a wide range of multiple air pollutant exposures in southern California and the large sample size.