Symptom guide · Pregnancy Smart
Linea nigra during pregnancy
By trimester
Weeks 1–13
1st trimester
The pale midline, called the linea alba, is always present, but visible darkening may not have started yet. A new painful, raised, scaly, or bleeding line is not typical linea nigra and should be shown to a clinician.
Weeks 14–27
2nd trimester
Linea nigra often becomes noticeable as pregnancy-related pigment activity increases. Sun exposure may deepen pigmentation, so ordinary sun protection can limit additional darkening, although it does not need to erase the line.
Weeks 28–birth
3rd trimester
The line may become darker or extend above the navel as pregnancy progresses. Its appearance does not reveal fetal sex or signal a pregnancy problem. Most fading happens gradually after birth rather than immediately after delivery.
What does the evidence show for linea nigra?
- MedlinePlus identifies linea nigra as the dark line that can develop along the middle of the abdomen during pregnancy. Pregnancy-related skin darkening is common, and sun exposure can make pigment changes more noticeable. 1
- A postpartum physiology review attributes pregnancy hyperpigmentation to increased pigment-stimulating activity associated with estrogen, progesterone, and melanocyte signaling. Linea nigra generally improves after birth, although fading can take months and may be incomplete. 2
- A published case described linea nigra appearing at 24 weeks in a 19-year-old first pregnancy and remaining visible three months postpartum. Because this is one case plus a narrative review, its timing and persistence cannot be generalized to every pregnancy. 3
- Most pregnancy-related skin color changes fade within a few months after delivery, although some pigment can remain. Persistent generalized itching, especially itching without a rash, is not an expected feature of linea nigra and should be reported because another pregnancy condition may be responsible. 1
- Validated prenatal cell-free DNA screening can provide information about fetal sex from a maternal blood sample beginning around 10 weeks. Abdominal pigmentation is not part of that testing, so linea nigra position, length, or darkness should not be used as a fetal-sex result. 4
When should I call my provider about linea nigra?
Linea nigra is flat and painless. Contact a clinician for persistent widespread itching, especially without a rash, or if the area is painful, raised, scaly, ulcerated, bleeding, or changing like a skin lesion rather than a uniform pigment line. Yellow skin or eyes, dark urine, or severe itching needs prompt pregnancy assessment. When in doubt, call your obstetric team the same day. Early input almost always beats waiting, and the on-call line exists exactly for this.
Frequently asked questions
What is linea nigra?
Linea nigra is the visible darkening of the normal vertical line in the center of the abdomen. The underlying line is present before pregnancy, but increased pigment activity can make it brown or darker and extend from the pubic area toward or above the navel.
When does linea nigra usually appear?
There is no single required week. It often becomes noticeable in the second trimester as pigmentation increases, but it may appear earlier, later, or not at all. A published case began at 24 weeks, which illustrates one course rather than a universal timetable.
Why does pregnancy cause a dark abdominal line?
Pregnancy increases pigment-stimulating hormonal activity, which can darken the nipples, face, scars, and the existing abdominal midline. Skin tone and individual pigment response influence how visible the line becomes. It is a pigment change, not a crack or scar.
Does linea nigra predict a boy or girl?
No reliable evidence supports using the line's length, side, or darkness to predict fetal sex. When medically appropriate and desired, prenatal cell-free DNA screening can provide fetal-sex information from about 10 weeks; abdominal pigmentation is not part of that method.
Does a line above the navel mean anything different?
No. Linea nigra may stop below the navel or continue above it, and the pattern can vary between pregnancies. The endpoint does not establish fetal sex, fluid level, fetal position, or pregnancy health.
When does linea nigra fade after pregnancy?
It usually lightens gradually over the first several months after birth as pregnancy-related pigment signaling decreases. Some color can remain longer or incompletely fade. One case remained visible at three months postpartum, which is compatible with gradual rather than immediate resolution.
Can sunlight make linea nigra darker?
Yes. MedlinePlus notes that sun exposure can intensify pregnancy pigmentation. Broad-spectrum sunscreen, shade, and clothing can reduce additional darkening. The line itself is benign and does not require a bleaching product.
Should linea nigra itch or hurt?
No. Linea nigra is a flat color change and should not itself cause pain, scaling, a raised rash, or significant itching. Persistent generalized itching, especially without a rash, or a painful, bleeding, rapidly changing skin lesion needs clinician review for another cause.
Is it normal not to develop linea nigra?
Yes. Visibility varies with baseline skin tone, genetics, sun exposure, and individual pigment response. Not developing a visible line does not indicate low pregnancy hormones, a fetal problem, or fetal sex.
Related in the library
References
Skin and hair changes during pregnancy
MedlinePlus · https://www.medlineplus.gov/ency/patientinstructions/000611.htm
Physiology, Postpartum Changes
NCBI Bookshelf · https://www.ncbi.nlm.nih.gov/books/NBK555904/
PubMed · https://pubmed.ncbi.nlm.nih.gov/38074022/
Prenatal Cell-Free DNA Screening
MedlinePlus · https://medlineplus.gov/lab-tests/prenatal-cell-free-dna-screening/
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