ICBDSR Report 2024

USA Texas BDES, 2015 to 2019

total births in the 5-year period: 1,946,187 (livebirths: 1,936,530)
average births per year: 389,240 (livebirths: 387,310)
terminations of pregnancy legal in country: Yes
data include terminations of pregnancy: Yes
source structure: Population-based

A word from the program about the program

TThe Texas BDES program is population-based with active case-ascertainment and covers the state of Texas in the southern USA.
The program monitors all deliveries to mothers residing in Texas at the time of delivery (approximately 380,000 annually) and captures data on infants/fetuses diagnosed with a birth defect or developmental disability monitored by Texas BDES within one year after delivery. Stillbirths and terminations of any gestational age are included. Data sources include birth hospitals, birthing centers, lay midwives, and hospitals where affected children are treated. Additionally, the program is now able to receive electronic case reports (eCR) for 26 birth defect conditions

Selected data highlights

Programs share aggregated information on selected major congenital anomalies for joint monitoring and evaluation. Programs may include additional anomalies in their activities. The following tables highlight key findings on the congenital anomalies selected for joint monitoring.

Top Ten by Frequency

Because of their frequency, these conditions impact the largest number of individuals and their families and are the most likely to be encountered in clinical practice. These top ten conditions are selected among those with significant clinical and public health impact. Ffor example, undescended testis is not included in this list.

Condition	Cases	Yearly Avg	Prevalence
Top 10 Conditions by Frequency
among specific diagnoses with major health impact, USA Texas BDES, 2015-2019 shown are total cases for the reporting period, yearly average cases, and prevalence per 10,000
Down syndrome	2816	563	14.5
Cleft lip with or without cleft palate	2077	415	10.7
Hydrocephaly	1648	330	8.5
Cystic kidney	1350	270	6.9
Neural tube defects, total	1339	268	6.9
Hypospadias	1196	239	6.1
Limb deficiency, total	1114	223	5.7
Coarctation of aorta	1097	219	5.6
Cleft palate without cleft lip	1052	210	5.4
Transposition of great vessels	1028	206	5.3
Note: not considered here are microcephaly, undescended testis, and unspecified conditions. However, microcephaly and undescended testis are included in the full table below. The green bar visually compares the prevalence (rows) relative to the most common condition in the table.

Notable Seven

These conditions were selected based on prior knowledge of their overall health impact (morbidity and mortality), regardless of frequency. This selection is the same for all programs. For example, neural tube defects and critical congenital heart disease are included as they may account in some programs for nearly half of all infant deaths associated with congenital anomalies.

Modifiable risk factors are well established for several of these conditions. This implication, as the potential for primary prevention, is unpacked in a later section (‘what if scenario’).

	Yearly cases		Percent liveborn	Prevalence per 10,000
Seven highly impactful conditions
selected on the basis of high morbidity and mortality, and potential for primary prevention USA Texas BDES, 2015-2019
	Program	Country	Percent liveborn	Prevalence per 10,000
Orofacial
Cleft lip with or without cleft palate	415	3923	94	10.7
Cleft palate without cleft lip	210	1980	96	5.4
Neural tube defects (NTD)
Neural tube defects, total	268	2530	75	6.9
Spina bifida	139	1320	94	3.6
Anencephaly	90	843	41	2.3
Heart
Transposition of great vessels	206	1943	99	5.3
Tetralogy of Fallot	175	1650	99	4.5
Hypoplastic left heart syndrome	94	880	99	2.4
Estimated from program prevalence extrapolated to total country births. United States births for 2022 from World Bank. The green bar visually compares the prevalence (rows) relative to the most common condition in the table.

The full table

This more expansive set of major congenital anomalies, internal and external, includes most conditions of significant clinical and public health impact. Most programs include these conditions, and some even more. Note that a child with multiple anomalies will be counted in all pertinent rows.

A later section provides a more detailed analysis of trisomy 21 (Down syndrome).

	All births			Livebirths
Selected congenital conditions by system
number of cases and prevalence (prev) per 10,000, for all births and livebirths USA Texas BDES, 2015-2019
	Cases	Prev	95% CI	Cases	Prev	95% CI
Neural tube defects (NTD)
Neural tube defects, total	1339	6.9	6.5 - 7.3	1004	5.2	4.9 - 5.5
Spina bifida	693	3.6	3.3 - 3.8	653	3.4	3.1 - 3.6
Anencephaly	451	2.3	2.1 - 2.5	186	1.0	0.8 - 1.1
Encephalocele	195	1.0	0.9 - 1.2	165	0.9	0.7 - 1.0
Other brain
Hydrocephaly	1648	8.5	8.1 - 8.9	1616	8.3	7.9 - 8.8
Microcephaly	386	2.0	1.8 - 2.2	381	2.0	1.8 - 2.2
Holoprosencephaly	250	1.3	1.1 - 1.5	231	1.2	1.0 - 1.3
Eye and Ear
Microtia	778	4.0	3.7 - 4.3	772	4.0	3.7 - 4.3
Microphthalmos	524	2.7	2.5 - 2.9	518	2.7	2.4 - 2.9
Anophthalmos	45	0.2	0.2 - 0.3	35	0.2	0.1 - 0.2
Anotia	43	0.2	0.2 - 0.3	36	0.2	0.1 - 0.2
Orofacial
Cleft lip with or without cleft palate	2077	10.7	10.2 - 11.1	1955	10.1	9.6 - 10.5
Cleft palate without cleft lip	1052	5.4	5.1 - 5.7	1014	5.2	4.9 - 5.6
Choanal atresia bilateral	124	0.6	0.5 - 0.8	121	0.6	0.5 - 0.7
Heart
Coarctation of aorta	1097	5.6	5.3 - 6.0	1090	5.6	5.3 - 6.0
Transposition of great vessels	1028	5.3	5.0 - 5.6	1022	5.3	5.0 - 5.6
Tetralogy of Fallot	875	4.5	4.2 - 4.8	869	4.5	4.2 - 4.8
Hypoplastic left heart syndrome	471	2.4	2.2 - 2.6	466	2.4	2.2 - 2.6
Gastrointestinal
Anorectal atresia/stenosis	957	4.9	4.6 - 5.2	902	4.7	4.4 - 5.0
Esophageal atresia	439	2.3	2.0 - 2.5	435	2.2	2.0 - 2.5
Small intestinal atresia/stenosis	400	2.1	1.9 - 2.3	397	2.1	1.8 - 2.3
Genitourinary
Undescended testis	3466	17.8	17.2 - 18.4	3448	17.8	17.2 - 18.4
Cystic kidney	1350	6.9	6.6 - 7.3	1335	6.9	6.5 - 7.3
Hypospadias	1196	6.1	5.8 - 6.5	1196	6.2	5.8 - 6.5
Renal agenesis	330	1.7	1.5 - 1.9	291	1.5	1.3 - 1.7
Epispadias	179	0.9	0.8 - 1.1	179	0.9	0.8 - 1.1
Indeterminate sex	89	0.5	0.4 - 0.6	45	0.2	0.2 - 0.3
Bladder exstrophy	24	0.1	0.1 - 0.2	23	0.1	0.1 - 0.2
Limb
Limb deficiency, total	1114	5.7	5.4 - 6.1	999	5.2	4.8 - 5.5
Polydactyly preaxial	856	4.4	4.1 - 4.7	854	4.4	4.1 - 4.7
Limb deficiency, transverse	514	2.6	2.4 - 2.9	447	2.3	2.1 - 2.5
Limb deficiency, preaxial	258	1.3	1.2 - 1.5	242	1.2	1.1 - 1.4
Limb deficiency, unspec.	158	0.8	0.7 - 0.9	136	0.7	0.6 - 0.8
Limb deficiency, axial	96	0.5	0.4 - 0.6	92	0.5	0.4 - 0.6
Limb deficiency, postaxial	54	0.3	0.2 - 0.4	53	0.3	0.2 - 0.3
Limb deficiency, intercalary	34	0.2	0.1 - 0.2	29	0.1	0.1 - 0.2
Limb deficiency, mixed	0	0.0	0.0 - 0.0	0	0.0	0.0 - 0.0
Abdominal
Gastroschisis	948	4.9	4.6 - 5.2	865	4.5	4.2 - 4.8
Diaphragmatic hernia	529	2.7	2.5 - 3.0	514	2.7	2.4 - 2.9
Omphalocele	442	2.3	2.1 - 2.5	355	1.8	1.6 - 2.0
Omphalocele/Gastroschisis, unspec.	206	1.1	0.9 - 1.2	148	0.8	0.6 - 0.9
Prune belly sequence	52	0.3	0.2 - 0.4	50	0.3	0.2 - 0.3
Chromosomal
Down syndrome	2816	14.5	13.9 - 15.0	2711	14.0	13.5 - 14.5
Trisomy 18	454	2.3	2.1 - 2.6	285	1.5	1.3 - 1.6
Trisomy 13	197	1.0	0.9 - 1.2	130	0.7	0.6 - 0.8
Note a dash (-) indicates data not available or not provided

A deeper look: comments from the program leads

The program leads provide their insights on data, operations, and recent achievements. Their interpretation of the data is particularly valuable because of their local experience and knowledge.

A data quality control assessment using statewide hospital discharge data, helped us to assess and improve our data surveillance completeness. Key achievements include increased data quality, leading to more complete facility discharge lists and more accurate data; better staff training, to improve consistency of method across the state; improved remote access to electronic medical records from facilities (now >90%); better ability to respond to and manage increasing demands and challenges from the Zika and COVID19 epidemics.
In addition, the program is focusing on increasing efficiency and interoperability (electronic data exchange) with other data systems, including the receipt of electronic case reports (eCR) for twenty-six birth defect conditions.
Finally, the program has been devoting more attention to family outreach activities, including NTD recurrence prevention, and referral of children with selected birth defects to services

Down syndrome (trisomy 21)

By far the most common chromosomal anomaly, Down syndrome is known to occur more frequently (has a higher risk of occurrence) in births of women with higher maternal age

This pattern is universally observed, provided there is no significant bias toward missing pregnancies with Down syndrome in older women (e.g., because of unreported pregnancy terminations)

	All cases			Livebirths
Down syndrome, overall and by maternal age
separately for all births and livebirths, prevalence per 10,000 (Poisson exact confidence intervals) USA Texas BDES, 2015-2019
	Cases	Prev	95% CI	Cases	Prev	95% CI
All maternal ages	2816	14.5	13.9 - 15.0	2711	14.0	13.5 - 14.5
< 20 years	99	7.0	5.7 - 8.6	98	7.0	5.6 - 8.4
20 to 24	295	6.6	5.9 - 7.4	286	6.5	5.7 - 7.2
25 to 29	428	7.6	6.9 - 8.4	410	7.3	6.6 - 8.0
30 to 34	561	11.2	10.3 - 12.2	534	10.7	9.8 - 11.6
35 to 39	824	33.9	31.6 - 36.2	793	32.8	30.5 - 35.0
40 to 44	552	107.9	99.1 - 117.3	537	105.9	97.0 - 114.8
45+ years	57	161.3	122.2 - 209.0	53	151.7	111.2 - 192.3
Age unspec.	0	-	-	0	-	-
Age unspec. = maternal age unknown or unspecified

Down syndrome - maternal age pyramid

Because of the relation between prevalence of Down syndrome and maternal age, the maternal age distribution in the population is a major determinant of the number of conceptions with Down syndrome in the population.

For programs that have maternal age specific data, one can compare the maternal-age ‘pyramid’ for all births in the population with that of births with Down syndrome. Typically, the distribution is skewed, with a relative excess of births with Down syndrome among the more advanced maternal age groups.

Down syndrome - birth rates matter

Despite the considerably higher risk (rates) of Down syndrome in mothers over 40 or 45 years, these age groups contribute comparatively fewer affected births than younger age groups. This is because birth rates matter: fewer births in the more advanced age groups mean fewer cases overall from those age groups.

A Pareto chart helps highlight the cumulative contribution of different age groups to the total number of cases. This information can help inform strategies for testing and counseling.

Linking risk factor profile and congenital anomalies

The term triple surveillance refers to a model of public health surveillance that births includes the full causal chain, from a) risk factors, which influence the number of affected pregnancies; to b) the affected pregnancies themselves, that are vulnerable to adverse health outcomes; and to c) the health outcomes in affected individuals. The burden of risk becomes expressed eventually in the burden of disease.

Historically, birth defect surveillance has focused on the second element, the occurrence of congenital anomalies.

However, improving outcomes (morbidity, mortality, disability) requires understanding and tracking risk factors (to improve primary prevention) and health outcomes (to improve care). Triple surveillance advocates integrating the tracking of all three elements in this causal chain. Together, these three domains provide clinicians, public health professionals, and policy makers with information to act.

To highlight such context, the next sections provide elements of country demographics, outcomes (mainly early mortality), and selected risk factors. These data, particularly those on risk factors and outcomes, are sometimes directly measured, and sometimes estimated. Birth defect programs with their partners can supplement these data with local assessments.

Country demographics

A surveillance program operates within its country’s demographic situation and trends. This information adds meaning and context to birth defect surveillance information.

Key Indicator	2022 data
Demographic Indicators, United States
on population, births, life expectancy
Total population	333,271,411
Number of births	3,665,986
Birth rate (per 1000 pop)	11.0
Fertility (births per woman)	1.7
Life expectancy at birth (years)	77.4
Source: World Bank (accessed Sept 2024)

From program to country

Many (though not all) programs cover a proportion of the country in which they operate. In this setting, a common question is what the program can tell use about the impact of congenital anomalies country-wide, under the assumption that the program information is a good estimator for the country itself. This assumption, of course, needs to be carefully examined, and the program staff typically has the local knowledge to help frame such estimates within the strengths and limitations of the data.

The table below uses the prevalence measured within the program to estimate the number of births with selected congenital anomalies for the entire country. These extrapolations have limitations, and in most cases are illustrative. However, at times a program that covers a proportion of the population may be the only practical window into congenital anomalies country-wide.

	All cases	liveborn
A window into the country: United States, 2022 estimates
Country-wide estimates for selected conditions (3,665,986 births), extrapolating from program data
Neural tube defects (NTD)
Neural tube defects, total	2522	1901
Spina bifida	1305	1236
Anencephaly	850	352
Encephalocele	367	312
Other brain
Hydrocephaly	3104	3059
Microcephaly	727	721
Holoprosencephaly	471	437
Eye and Ear
Microtia	1466	1461
Microphthalmos	987	981
Anophthalmos	85	66
Anotia	81	68
Orofacial
Cleft lip with or without cleft palate	3912	3701
Cleft palate without cleft lip	1982	1920
Choanal atresia bilateral	234	229
Heart
Coarctation of aorta	2066	2063
Transposition of great vessels	1936	1935
Tetralogy of Fallot	1648	1645
Hypoplastic left heart syndrome	887	882
Gastrointestinal
Anorectal atresia/stenosis	1803	1708
Esophageal atresia	827	823
Small intestinal atresia/stenosis	753	752
Genitourinary
Undescended testis	6529	6527
Cystic kidney	2543	2527
Hypospadias	2253	2264
Renal agenesis	622	551
Epispadias	337	339
Indeterminate sex	168	85
Bladder exstrophy	45	44
Limb
Limb deficiency, total	2098	1891
Polydactyly preaxial	1612	1617
Limb deficiency, transverse	968	846
Limb deficiency, preaxial	486	458
Limb deficiency, unspec.	298	257
Limb deficiency, axial	181	174
Limb deficiency, postaxial	102	100
Limb deficiency, intercalary	64	55
Abdominal
Gastroschisis	1786	1638
Diaphragmatic hernia	996	973
Omphalocele	833	672
Omphalocele/Gastroschisis, unspec.	388	280
Prune belly sequence	98	95
Chromosomal
Down syndrome	5304	5132
Trisomy 18	855	540
Trisomy 13	371	246
Note: includes conditions with at least 5 estimated cases. Assumes that prevalence estimates from program are valid country-wide.

Outcomes - early mortality

The relative impact of congenital anomalies on early mortality (neonatal, infant, and under 5 years) tends to increase as infant mortality due to other causes falls. This pattern has been observed worldwide. These general indicators of early mortality are tracked regularly by public health agencies.

Key Indicator	2022 data
Mortality Indicators, United States
Neonatal mortality (per 1000)	3.2
Infant mortality (per 1000)	5.4
Under 5 mortality (per 1000)	6.3
Source: World Bank, accessed Sept 2024. The green bar visually compares the indicators (rows) relative to the indicator with the highest value.

Outcomes - mortality with congenital anomalies

A more specific indicator (infant deaths due to congenital anomalies) is more challenging to document accurately. Missed diagnoses, especially of internal anomalies, can lead to massive underestimates, especially in settings where diagnoses rely only or mostly on an external exam. The table below summarizes data and estimates from systematic public sources. However, local assessments from birth defect surveillance program can help improve the quality of this key indicator.

Age group	Percent	Deaths / 100k pop
Deaths due to birth defects, United States
among infants (< 1 year old) and from first to fifth birthday
Infants	19.9	98.1
1 to < 5 yrs	10.8	2.6
Source: WHO mortality data for 2021 \| who.int. The green bar visually compares the indicators (rows) relative to the indicator with the highest value.

Risk factors

Some modifiable exposures are well-established risk factors for congenital anomalies. Reducing these exposures is the basis for effective primary prevention. Here we focus specifically on smoking, diabetes, and folate insufficiency. These factors, both common and modifiable, increase the risk of major contributors to morbidity and mortality, including orofacial clefts, neural tube defects, and serious congenital heart disease. The impact of these risk factors depend on their frequency in the population. The following tables show frequency estimates for the country. In another section, these data are used to estimate the number of cases in the country potentially preventable by eliminating the risk factors.

Smoking

Smoking is associated with increased risk for many adverse pregnancy outcomes and several congenital anomalies, including orofacial clefts and probably congenital heart disease. The increased risk is relatively modest (odds ratios tipically less than 1.5) but the effect size, or number of cases due to smoking, depends on the rate of smoking among women who become pregnant. Here we used country-specific estimates of smoking in women of reproductive age (see table for references). Rates of smoking during pregnancy tend to be lower, but by the time many women know they are pregnant, the at-risk period for congenital anomalies has often already passed.

Women	Frequency (%)
Smoking in women
Frequency in two different groups, United States
Of reproductive age	16.1 ( 14.0 - 18.5 )
During pregnancy	17.4 ( 16.0 - 18.8 )
Source: IHME \| www.healthdata.org \| and Lange 2018

Diabetes

Maternal pregestational diabetes is associated with increased risk for many serious congenital anomalies, including spina bifida, several critical congenital heart defects, and multiple congenital anomalies, among others. In some cases the relative risk (or odds ratio) can be quite high, above 4 or 5 in some cases. The effect size (number of cases due to diabetes) depends on the frequency of diabetes, which tipically increases with age.

Age Group	Percent
Diabetes in women
Frequency by age group, United States
15 to 19	0.8
20 to 24	1.2
25 to 29	1.8
30 to 34	2.7
35 to 39	4.0
40 to 44	5.6
45 to 49	7.7
Source: IHME \| www.healthdata.org

Folate insufficiency

Folate insufficiency is associated with increased risk for neural tube defects and perhaps other congenital anomalies. On a population-basis, well-implemented folic acid fortification is estimated to decrease the prevalence of neural tube defects below 6 per 10,000 or perhaps even lower. Folic acid fortification is most effective when it is mandatory and universal, meaning that it involves foods commonly consumed by large parts of the population (e.g., wheat, maize, rice, depending on culture and geography).

Mandatory	Food vehicle	Year started
Folic acid fortification
Status of mandatory fortification in United States
Yes	Wheat flour	1998
Yes	Rice	1998
Source: Country program and FFI \| fortificationdata.org

What if - prevention scenarios

What follows is a tricky but important exercise. By combining information about risk factors and prevalence of congenital anomalies, one can attempt to estimate the number of cases attributable to risk factors. This is illustrated in the table below, which uses prevalence information from the program and risk factor information (e.g., diabetes frequency in women) from country data. These estimates also require knowing the relative risk of disease given the exposure. Here we use odds ratios derived from high quality studies and metanalyses. These data then are fed into the Levine estimator of attributable fraction to generate the scenarios that you see in the table. For neural tube defects, we used a different approach. We used 6 per 10,000 as the (conservative) estimate of the birth prevalence achievable by fully implemented folate fortification, and postulated that a prevalence in excess of this value consists of cases attributable to folate insufficiency (as relates to neural tube defect prevention).

	Prevalence per 10,000	attributable cases			Risk factor parameters
Attributable cases for selected risk factors
yearly estimates in program and in country, and per million births USA Texas BDES, 2015-2019
	Prevalence per 10,000	Program	Country	per 1M births	Risk factor parameters
Orofacial
Cleft lip with or without cleft palate	10.7	22	204	56	smoking, freq: 16.1%, OR: 1.34
Cleft palate without cleft lip	5.4	7	68	18	smoking, freq: 16.1%, OR: 1.22
Neural tube defects (NTD)
Neural tube defects, total	6.9	35	330	90	Presumed folate insufficiency, prevalence > 6
Heart
Transposition of great vessels	5.3	8	79	21	diabetes, freq: 1.8%, OR: 3.34
Tetralogy of Fallot	4.5	11	108	29	diabetes, freq: 1.8%, OR: 4.89
Hypoplastic left heart syndrome	2.4	6	53	15	diabetes, freq: 1.8%, OR: 4.58
Odds ratios from literature, exposure frequencies from country estimates (see methods for details). Estimates for neural tube defects are provided only when reported prevalence is greater than 6 per 10,000. Note that for programs that do not include stillbirths or terminations of pregnancy, these may be underestimates.

Arguably, these estimates are simplistic. For one, they assume accurate inputs and lack of interactions between risk factors. For neural tube defects, for example, the assumption is that the reported prevalence is accurate (e.g., that it includes stillbirths and pregnancy terminations) and that the excess prevalence is entirely due to (or preventable by) the folate status of the population.

For smoking and diabetes, these estimates assume, for example, that the reported smoking rates in women reflect the smoking rates in the at-risk period, typically the periconceptional period. Smoking rates in pregnancy are typically lower than rates among women of childbearing age, but many women realize they are pregnant after the at-risk period for many congenital anomalies. One may argue that the true smoking rates in the at-risk period are somewhere between these two estimates .

Finally, the computation of attributable cases in these scenarios considers risk factors ‘one at the the time’ and does not account, for example, for multiple exposures (e.g., diabetes and smoking) or interactions among multiple exposures. And so on.

Nevertheless, even rough estimates provide an important message. Some instances, perhaps many, of major and even lethal congenital anomalies are preventable by reducing the burden of risk in populations and individuals. Moreover, for many risk factors (smoking and diabetes in particular), the benefits of exposure mitigation extend beyond the prevention of congenital anomalies to the prevention of many other health conditions, for the fetus as well as for parents.